IC:2021-06-15, psp, osal, cfe

nasa/cFE#1619 - cfe v6.8.0-rc1+dev693
nasa/osal#1076 - osal v5.1.0-rc1+dev530
nasa/PSP#296 - psp v1.5.0-rc1+dev118

*Documentation Updates:*

nasa/cFE#1598, Updated FS Read/WriteHeader API return documentation
nasa/cFE#1601, Document CFE_ES_RunLoop increment task counter behavior
nasa/cFE#1602, Document CFE_TBL_Unregister use-case
nasa/cFE#1603, Update version description per current design

*Standardize docs generation:*

nasa/cFE#1615, standardize on "docs" subdirectory
nasa/osal#1071, rename doc to docs
nasa/PSP#294, rename doc to docs

*Coding Standard:*

nasa/osal#1042
nasa/PSP#292

**Mutex for UTAssert**

nasa/cFE#1596, provide CFE assert lock/unlock
nasa/osal#1065, add mutex lock around UtAssert globals

*Resolve API-UT discrepancies:*

nasa/osal#1055, idmap API
nasa/osal#1056, file API
nasa/osal#1057, filesys API
nasa/osal#1060, socket API
nasa/osal#1064, select API

**Other cFE ixes**

nasa/cFE#1566, Simplify CFE_FS_SetTimestamp and fix syslog typo
nasa/cFE#1592, Removed redundant check/set of CFE_CPU_ID_VALUE
nasa/cFE#1593, add time get reference error bit
nasa/cFE#1600, Add workflow to build cFE documentation
nasa/cFE#1609, Requirements updates
nasa/cFE#1610, ES/ResourceID documentation cleanup
nasa/cFE#1613, allow multiple sources in add_cfe_coverage_test
nasa/cFE#1586, add ES Misc Functional test
nasa/cFE#1607, add Mempool functional tests
nasa/cFE#1605, Clean/simplify version header and reporting
nasa/cFE#1612, doxygen cleanup
nasa/cFE#1611, Prepend system log messages with function name

nasa/osal#1063, const correct OS_SelectFdIsSet
nasa/osal#1073, Fix OS_Select doxygen errors
nasa/osal#1073, Add missing OS_Select param doc
nasa/osal#1067, Add Workflow to build and verify OSAL API Guide
nasa/osal#1070, add detail design template
nasa/osal#1072, Update error codes and documentation
nasa/osal#1075, Increase UT object limit for testing

Co-authored-by: Jacob Hageman <skliper@users.noreply.github.com>
Co-authored-by: Joseph Hickey <jphickey@users.noreply.github.com>
Co-authored-by: Ariel Adams <ArielSAdamsNASA@users.noreply.github.com>
Co-authored-by: Alex Campbell <zanzaben@users.noreply.github.com>
Co-authored-by: Jose F Martinez Pedraza <pepepr08@users.noreply.github.com>