Added reference documentation

README.md

@@ -11,9 +11,12 @@ This bundle has not been fully verified as an operational system, and is provide
 
 The cFS Framework is a core subset of cFS.  There are additional OSALs, PSPs, and tools as listed below available from a variety of sources.
 
-## References to Auto-generated Documentation
+## References Documentation
   - cFE User's Guide: https://github.com/nasa/cFS/blob/gh-pages/cFE_Users_Guide.pdf
   - OSAL User's Guide: https://github.com/nasa/cFS/blob/gh-pages/OSAL_Users_Guide.pdf
+  - cFE App Developer's Guide: https://github.com/nasa/cFE/blob/main/docs/cFE%20Application%20Developers%20Guide.md
+  - Training documentation: https://ntrs.nasa.gov/citations/20205000691
+  - cFS Overview: https://cfs.gsfc.nasa.gov/cFS-OviewBGSlideDeck-ExportControl-Final.pdf
 
 ## Release Notes