[Chapel Merge] Update the language spec on ref variables

Branch: refs/heads/main
Revision: 03e122cda394c7397aedd4b33106af923caf17ca
Author: vasslitvinov
Link: Update the language spec on ref variables by vasslitvinov · Pull Request #23996 · chapel-lang/chapel · GitHub
Log Message:
Update the language spec on ref variables (#23996)

Adding more specification of ref variables and a related open issue.

r: @dlongnecke-cray - thanks!

Compare: Comparing 39a9f6f5083091ac14576bf1872159e587a09579...fba68d74c69d530d39815edc5e2309e06698912a · chapel-lang/chapel · GitHub

Diff:
M doc/rst/language/spec/procedures.rst
M doc/rst/language/spec/variables.rst
https://github.com/chapel-lang/chapel/pull/23996.diff