Document v3 binary size checks

[rupayon123]

Summary

• add a v3 docs page for measuring and reducing Go binary size
• document that v3 currently does not define urfave_cli_no_* build tags
• add practical commands for go build, go version -m, and go tool nm
• link the page from the v3 MkDocs nav

Why

Addresses #2365 with a concise starting point for users who want to understand where binary size comes from before proposing build tags or package splits.

Validation

• git diff --check
• inspected the generated Markdown content locally

I did not run the MkDocs build because mkdocs is not installed in my local Python environment.

[rupayon123]

I reran local checks with Go installed and the pinned docs dependencies:

• go test ./... — passed
• mkdocs build --strict — passed

Marking this ready for review.

[dearchap]

Review of PR #2366

This is a well-written, practical documentation page that addresses issue #2365. The content is accurate and useful. A few suggestions:

1. Add a link to new-issue page (line ~50) — The paragraph says "open an issue" but does not provide a URL. Add a link to https://github.com/urfave/cli/issues/new for convenience.

2. Mention make check-binary-size — The PR title says "binary size checks" but the page doesn't reference the existing make check-binary-size target already in the Makefile/scripts. This is the most relevant CI check and would be worth mentioning.

3. Combine the two go build examples — Showing -trimpath and -ldflags="-s -w" in separate code blocks is fine, but many readers will want the release recipe as one command. Consider adding a combined example like:

go build -trimpath -ldflags="-s -w" -o myapp ./path/to/main

4. Remove "already" — Line 1: s/Go already removes/Go removes/ for tighter prose.

5. Section order — Consider moving "Current v3 Build Tags" after "Practical Checks". The reader benefits from learning how to measure before learning about v3-specific tag caveats.

The mkdocs.yml change is indented correctly and follows the existing nav pattern.

[rupayon123]

Thanks for the detailed pass. I updated the page with the issue link, make check-binary-size, a combined release-build command, the wording cleanup, and moved the build-tag caveat after the practical checks.

I reran go test ./..., make check-binary-size, and mkdocs build --strict; all pass.

[rupayon123]

Thanks for the review and merge. Glad the docs update landed; I followed you here too so I can keep up with the project.