[Chapel Merge] Update and consolidate `README.devel` and `README.files`

Branch: refs/heads/main
Revision: a8d7fc2652ad93f02a8b1896e0f2a1f6174579f6
Author: arifthpe
Link: Update and consolidate `README.devel` and `README.files` by arifthpe · Pull Request #28860 · chapel-lang/chapel · GitHub
Log Message:
Update and consolidate README.devel and README.files (#28860)

Make some updates and improvements to the README.devel and
README.files files:

  • Use alphabetical order consistently.
  • Remove reference to README file (now README.rst).
  • Add in files and directories that were not listed, into the respective
    README.

[reviewed by @bradcray , thanks!]

Compare: Comparing 915439f15d96d36ce9ffa6be5926c57a125148c2...8acf7bb90384610e47291acd0df85df9a19dcb19 · chapel-lang/chapel · GitHub

Diff:
M README.devel
M README.files
https://github.com/chapel-lang/chapel/pull/28860.diff