Fix url-pattern for top section pages

[pedro-psb]

The section pages (User Manual, Dev Manual, Help) have the url in the format: /pulp-docs/docs/sections/{section-name}/, because they live inside pulp-docs in that location.

This doesn't look very good and should be something like /{section-name}, regardless of where the section files live.

To summarize:

# before
pulpproject.org/
pulpproject.org//pulp-docs/docs/sections/user/
pulpproject.org//pulp-docs/docs/sections/dev/
pulpproject.org//pulp-docs/docs/sections/blog/
pulpproject.org//pulp-docs/docs/sections/help/

# after
pulpproject.org/
pulpproject.org/user/
pulpproject.org/dev/
pulpproject.org/blog/
pulpproject.org/help/