docs: Fix broken links in "Perf benchmarking and tuning" section

[yinggeh]

What does the PR do?

• Go to https://docs.nvidia.com/deeplearning/triton-inference-server/user-guide/docs/perf_benchmark/perf_analyzer.html and click any link. For example, Concurrency Mode URL is broken.
• Remove duplicate *.rst files and creates Overview sections to display *.md docs.
• Other improvements

Checklist

• PR title reflects the change and is of format <commit_type>: <Title>
• Changes are described in the pull request.
• Related issues are referenced.
• Populated github labels field
• Added test plan and verified test passes.
• Verified that the PR passes existing CI.
• Verified copyright is correct on all changed files.
• Added succinct git squash message before merging ref.
• All template sections are filled out.
• Optional: Additional screenshots for behavior/output changes with before/after.

Commit Type:

Check the conventional commit type
box here and add the label to the github PR.

• docs

Related PRs:

Where should the reviewer start?

Test plan:

• CI Pipeline ID:
  43832969

Caveats:

Background

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• closes GitHub issue: Broken links in Perf Analyzer documentation #8551

[whoisj]

Looks good, thanks for catching all of these. Left a minor (I hope) request.