Fix links to spec documents, migrated from rst to md

mongodb/specifications#1520

Author: GromNaN

CONTRIBUTING.md

@@ -138,15 +138,15 @@ The test suite references the following environment variables:
    [drivers-evergreen-tools](https://github.com/mongodb-labs/drivers-evergreen-tools).
    If undefined or inaccessible, tests requiring certificates will be skipped.
 
-The following environment variable is used for [stable API testing](https://github.com/mongodb/specifications/blob/master/source/versioned-api/tests/README.rst):
+The following environment variable is used for [stable API testing](https://github.com/mongodb/specifications/blob/master/source/versioned-api/tests/README.md):
 
  * `API_VERSION`: If defined, this value will be used to construct a
    [`MongoDB\Driver\ServerApi`](https://www.php.net/manual/en/mongodb-driver-serverapi.construct.php),
    which will then be specified as the `serverApi` driver option for
    [`MongoDB\Driver\Manager`](https://www.php.net/manual/en/class.mongodb-driver-manager.php)
    objects created by the test suite.
 
-The following environment variables are used for [CSFLE testing](https://github.com/mongodb/specifications/blob/master/source/client-side-encryption/tests/README.rst):
+The following environment variables are used for [CSFLE testing](https://github.com/mongodb/specifications/blob/master/source/client-side-encryption/tests/README.md):
 
  * `CRYPT_SHARED_LIB_PATH`: If defined, this value will be used to set the
    `cryptSharedLibPath` autoEncryption driver option for

tests/causal-consistency/causal-consistency-001.phpt

@@ -2,7 +2,7 @@
 Causal consistency: new session has no operation time
 --DESCRIPTION--
 Causal consistency spec prose test #1
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>

tests/causal-consistency/causal-consistency-002.phpt

@@ -2,7 +2,7 @@
 Causal consistency: first read in session does not include afterClusterTime
 --DESCRIPTION--
 Causal consistency spec prose test #2
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>

tests/causal-consistency/causal-consistency-003.phpt

@@ -2,7 +2,7 @@
 Causal consistency: first read or write in session updates operationTime
 --DESCRIPTION--
 Causal consistency spec prose test #3
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>

tests/causal-consistency/causal-consistency-004.phpt

@@ -2,7 +2,7 @@
 Causal consistency: first read or write in session updates operationTime (even on error)
 --DESCRIPTION--
 Causal consistency spec prose test #3
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>

tests/causal-consistency/causal-consistency-005.phpt

@@ -2,7 +2,7 @@
 Causal consistency: second read's afterClusterTime uses last reply's operationTime
 --DESCRIPTION--
 Causal consistency spec prose test #4 and #5
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>

tests/causal-consistency/causal-consistency-006.phpt

@@ -2,7 +2,7 @@
 Causal consistency: second read's afterClusterTime uses last reply's operationTime (even on error)
 --DESCRIPTION--
 Causal consistency spec prose test #4 and #5
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>

tests/causal-consistency/causal-consistency-007.phpt

@@ -2,7 +2,7 @@
 Causal consistency: reads in non-causally consistent session never include afterClusterTime
 --DESCRIPTION--
 Causal consistency spec prose test #6
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>

tests/causal-consistency/causal-consistency-008.phpt

@@ -2,7 +2,7 @@
 Causal consistency: reads in causally consistent session never include afterClusterTime for unsupported deployment
 --DESCRIPTION--
 Causal consistency spec prose test #7
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>

tests/causal-consistency/causal-consistency-009.phpt

@@ -2,7 +2,7 @@
 Causal consistency: default read concern includes afterClusterTime but not level
 --DESCRIPTION--
 Causal consistency spec prose test #8
-https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.rst#test-plan
+https://github.com/mongodb/specifications/blob/master/source/causal-consistency/causal-consistency.md#test-plan
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
 <?php skip_if_not_libmongoc_crypto(); ?>