[Chapel Merge] Add technote about manage statement, add 'manage'

Branch: refs/heads/main
Revision: 42fbf04
Author: dlongnecke-cray
Log Message:

Merge pull request #18418 from dlongnecke-cray/add-manage-technote

Add technote about manage statement, add 'manage' keyword to spec

Write a technote about the manage statement that describes how it
works today, as well as its current status and open questions.

Add manage to the list of keywords in the "Lexical Structure"
section of the spec.

Reviewed by @arezaii and @lydia-duncan. Thanks!

Signed-off-by: David Longnecker dlongnecke-cray@users.noreply.github.com

Modified Files:
A doc/rst/technotes/manage.rst

M doc/rst/language/spec/lexical-structure.rst
M doc/rst/technotes/index.rst

Compare: https://github.com/chapel-lang/chapel/compare/c8c0647369a4...42fbf0440dca