CI: Adding script to validate consistent and correct capitalization among headings in documentation (#26941)
Closes #26941

This script should be running correctly to validate capitalization for various rst files.  Many keywords will need to be added into the script as more and more files are tested on this script. Currently testing on the following rst files through code_checks.sh:

doc/source/development/contributing.rst
doc/source/index.rst doc/source/ecosystem.rst

contributing.rst and ecosystem.rst should produce an exit code of 1, indicating there are incorrect capitalization in their headings.