Merge branch 'barry/2023-02-15/refactor-doc-subdirectories' into 'main'

Remove confusing and un-need docs directory that contains manual

See merge request petsc/petsc!6078

Remove confusing and un-need docs directory that contains manual

Commit-type: housekeeping

Merge branch 'psanan/docs-sphinx-man-pages' into 'main'

Integrate Man Pages into Sphinx Docs

Closes #1132 and #1015

See merge request petsc/petsc!4989

Docs: add manual page redirects

For the dirhtml docs buld, add a script to add HTML files for all
previous man page locations, e.g.

docs/manualpages/Foo/Bar.html

linking to the new dirhtml loca

Docs: add manual page redirects

For the dirhtml docs buld, add a script to add HTML files for all
previous man page locations, e.g.

docs/manualpages/Foo/Bar.html

linking to the new dirhtml locations, e.g

docs/manualpages/Foo/Bar/index.html

show more ...