Update product name and doc structure

[clayton-cornell]

PR Description

This PR does the following:

• Delete Static docs
• Delete Operator docs
• Move Flow docs up a level and removes flow from doc path
• Update the PRODUCT_NAME and PRODUCT_ROOT_NAME variables
• Update the Makefile and variables.mk files so make docs will build a local version of the docs
• Simplify the aliases in the metadata
• Update the canonical URL in the metadata
• Do an initial pass on the root _index.md to combine some info that was split in the old repo. (currently disconnected from the generated template topic)
• Combine some information into the Introduction topic
• Fix the links in the root topics - docs/reference is removed and in its place we use relative URIs. This simplifies the linking within the doc tree and will work in both OSS and Cloud doc mounts
• Clean up some of the text, duplicate or broken links, etc.
• Fix the links in the tutorials topics.
• Fix links in the tasks topics
• Fix links in reference topics
• Clean up relrefs and convert to relative URIs
• Fix various broken links and add back missing links (missing in Agent topics too)

Which issue(s) this PR fixes

Notes to the Reviewer

PR Checklist

• CHANGELOG.md updated
• Documentation added
• Tests updated
• Config converters updated

[clayton-cornell]

@rfratto I've got some conflicts in docs/sources/static in files that I want to delete... not sure how to resolve this though. Any tips?

[rfratto]

@clayton-cornell When you're trying to merge grafana/alloy:main into your branch (or rebase, whatever you prefer) and you're resolving the merge conflicts, you can git rm -r docs/sources/static and git rm -r docs/sources/operator to tell Git to resolve by deleting the files. I'm not 100% sure I have the commands right, but I think that's how you'd do it

[rfratto]

@clayton-cornell Also when you merge this PR, make sure you're using Squash and merge; that's what we normally enforce but since all three types of merging are temporarily enabled you have to make sure it's explicitly set that way.

[clayton-cornell]

@rfratto Thanks that tip got me moving with fixing things.

I also had to modify internal/tools/docs_updated_test.go and internal/tools/links_to_types.go to remove /flow from the doc test path... flow isn't in the Alloy doc path, so it was failing on a file not found. All seems to work OK, now, but since I've changed something outside my corner of the source, I'd like a quick check on this.

The doc source changes are too big to check. I've ran local doc builds and made sure the docs build without errors.. so should be good as a solid base to iterate on.

[jdbaldry]

Yeah pages look fine at a scan. Let me know if there's anything specific you'd like me to check. Otherwise we can get this in and iterate in smaller chunks.

[clayton-cornell]

I'm going to merge.. the two Go files I touched need a major rework anyway. I changed two lines to get the docs to build. It's not in the core product, and it's given me a green build.