[Chapel Merge] Document recommended adjustment to operator method

Branch: refs/heads/main
Revision: 9db468e
Author: lydia-duncan
Log Message:

Merge pull request #17963 from lydia-duncan/inheritanceAndOps

Document recommended adjustment to operator methods for inheritance
[reviewed by @mppf]

For now, we recommend declaring class arguments to operator methods as
borrowed to work around an issue with inheritance and owned. Document that

Also, add a test that ensures this pattern works.

Resolves Cray/chapel-private#2180

Checked that the result of make docs looked good and that the test passed a
fresh checkout.

Modified Files:
A test/functions/operatorOverloads/operatorMethods/inheritance-works.chpl

A test/functions/operatorOverloads/operatorMethods/inheritance-works.good
M doc/rst/technotes/operatorMethods.rst

Compare: https://github.com/chapel-lang/chapel/compare/c00e0610bdb9...9db468ef4a9f