Add missing RST files and resolve duplicate object description issues in documentation

[behnazh-w]

The recent PR on adding support for JFrog and Witness provenances has added modules but no RST files for them. Note that we use

sphinx-apidoc --no-toc --module-first --force --maxdepth 1 --output-dir docs/source/pages/apidoc/ src/

to automatically generate these files. Also, there are various duplicate object description issues that need to be resolved.