Update from.md

Author: soerenwolfers

docs/preview/sql/query_syntax/from.md

@@ -119,6 +119,35 @@ SELECT sum(t.i)
 WHERE i % 2 = 0;
 ```
 
+### Table functions
+
+Some functions in duckdb return entire tables rather than individual values. These functions are accordingly called _table functions_ and can be used with a `FROM` clause like regular table references. 
+Examples include `read_csv`, `read_parquet`, `range`, `generate_series`, `repeat`, `unnest`, `glob`. For example, the previous example
+
+
+```sql
+SELECT *
+FROM 'test.csv';
+```
+
+is implicitly translated to 
+
+
+```sql
+SELECT *
+FROM read_csv('test.csv');
+```
+
+All table functions support a `WITH ORDINALITY` prefix, which extends the returned table by an integer column `ordinality` that enumerates the generated rows starting at `1`.
+
+```sql
+SELECT * 
+FROM read_csv('test.csv') WITH ORDINALITY;
+```
+
+Note that the same result could be achieved using the `row_number` window function.
+
+
 ## Joins
 
 Joins are a fundamental relational operation used to connect two tables or relations horizontally.