Checklist

• I reviewed the Contributing Guide.
• I performed a cursory search to see if the bug report is relevant, not redundant, nor in conflict with other tickets.

Describe the bug
The cFE Developer's Guide has a few out-date-references to functions/variables that have changed, some typos and a few broken links in the table of contents.

Code snips

• References to cfe_testrunner module that was removed in Fix #1281, remove testrunner and convert testcase to app #1292
• Out-of-date names: CFE_MSG_GetTime, CFE_TIME_VALID, CFE_TIME_INVALID, CFE_TIME_FLYWHEEL

Expected behavior
Docs should be up-to-date and correct.

Reporter Info
Avi Weiss @thnkslprpt