[Chapel Merge] Update the documentation for operator changes

Branch: refs/heads/master
Revision: 7d01bba
Author: lydia-duncan
Log Message:

Merge pull request #17356 from lydia-duncan/updateDocOp

Update the documentation for operator changes
[reviewed by @mppf and @cassella]

Adds a special production using the operator keyword to the syntax tree for
procedures. In doing so, remove the operator names from the potential naming
scope of other procedures, and remove the production that enabled both to be
used. In doing so, explicitly call out by and align as operator names, as they
would no longer be covered otherwise.

In the operator overloading section, explicitly call out that operator overloads
should be defined using the keyword, and fix the table so it renders properly.

Replace proc in the records section demonstrating overloading == and !=
with operator.

Adds a new technote for operator methods, since those are still in progress.

Updates the specialMethods primer to no longer say operators need two
arguments (which was never true), to no longer say they can't be methods (but
not to explicitly say they can be until we are more certain of their stability), and
to say to use the operator keyword.

Resolves Cray/chapel-private#1764

Double checked result of make docs and that test/release/examples all passed
after a make spectests

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

M doc/rst/language/spec/interoperability.rst
M doc/rst/language/spec/methods.rst
M doc/rst/language/spec/procedures.rst
M doc/rst/language/spec/records.rst
M doc/rst/technotes/index.rst
M test/release/examples/primers/specialMethods.chpl

Compare: https://github.com/chapel-lang/chapel/compare/035e96c3fa2d...7d01bba85e53