Updates user guide page names and links

[LappleApple]

Updated a number of page names that were vague in the context of other pages (GitOpsSets, Pipelines, GitOps Run sections), and fixed resulting broken links. Minor punctuation and other fixes scattered throughout. PR also updates the sidebars.js for main and last version (0.28.0) and the 0.28.0 docs.

The linter snagged on a reference in the "Install WGE" page to our Helm reference page, but I didn't edit that page. The link looks fine, so not sure what's going on.

[enekofb]

Reviewed the section within website/docs as i assumed is the main part and the part on v0.28 are backporting or adjusting changes but not new content.

it looks generally good, added small comments to enhance it.

Also added a question about the cert-manager section within tls. it seems there is something missing in terms of scope or content.

[enekofb]

replied and expanded to the open items.

[enekofb]

Thanks for taking into consideration the comments.

The cert-manager section seems still having some changes in this PR. Not sure if that is expected. Asked in the thread,

Regarding aligning getting started, there are some other docs that might require the same alignment. Suggested in this comment. For example this suggestion. There might be other ones. It could be good to review to ensure we have consistency.

Last comment, is given we are in v0.29 whether makes sense to just dont backport the changes of this PR to v0.28 or if there is anything in particular we are looking in that version.

[enekofb]

Approved: thanks for the patient to take the suggestions.

Before merging please check the build job. I think that you dont need this change or it is left behind from cleanup

It would be great to squash and merge the branch or squash the commits before merging