docs(v2): add binary size guide and mkdocs navigation for v2 build tags

docs/v2/binary-size.md

@@ -0,0 +1,85 @@
+# Binary Size
+
+Go removes unreachable code during compilation. The first step in size optimization
+is measuring the shipped executable rather than assuming a feature introduces overhead.
+
+```sh-session
+go build -trimpath -o myapp ./cmd/myapp
+ls -lh myapp
+```
+
+## Compiler and Linker Flags
+
+For release builds, combine path trimming with symbol table and debug metadata removal:
+
+```sh-session
+go build -trimpath -ldflags="-s -w" -o myapp ./cmd/myapp
+ls -lh myapp
+```
+
+### Flag Breakdown
+
+- `-trimpath`: Strips local file system paths from the compiled executable. This removes
+  machine-specific directory paths from panic stack traces, produces reproducible
+  binaries, and reduces string data size.
+- `-ldflags="-s -w"`:
+  - `-s`: Omits the symbol table.
+  - `-w`: Omits DWARF debugging information.
+
+Panic stack traces retain function names and line offsets because the Go runtime
+maintains internal program counter tables in a distinct section.
+
+## Inspecting Binary Contents
+
+Use the Go toolchain to inspect embedded build metadata and symbol allocations on an unstripped binary:
+
+```sh-session
+go version -m myapp
+go tool nm -size myapp | sort -k2,2nr | head -40
+```
+
+- `go version -m`: Displays module dependencies, Go toolchain version, build tags, and
+  compiler flags embedded in the binary.
+- `go tool nm -size`: Lists symbols sorted by size, identifying the largest functions
+  and data structures. Run this command against an unstripped binary, as `-s` removes
+  the symbol table.
+
+## Build Tags in v2
+
+In `urfave/cli/v2`, two build tags prune optional dependencies and features at compile time:
+
+| Build Tag | Target Feature | Dependency Removed | Approximate Savings |
+|-----------|----------------|--------------------|---------------------|
+| `urfave_cli_no_docs` | Markdown and man page generation (`ToMarkdown`, `ToMan`) | Documentation generator packages | 300 to 400 KB |
+| `urfave_cli_no_suggest` | Command and flag typo suggestions ("Did you mean?") | `github.com/xrash/smetrics` | Variable |
+
+### Usage
+
+To build without documentation generation methods:
+
+```sh-session
+go build -tags urfave_cli_no_docs -trimpath -ldflags="-s -w" -o myapp ./cmd/myapp
+```
+
+To build without typo suggestions:
+
+```sh-session
+go build -tags urfave_cli_no_suggest -trimpath -ldflags="-s -w" -o myapp ./cmd/myapp
+```
+
+To combine both build tags:
+
+```sh-session
+go build -tags "urfave_cli_no_docs urfave_cli_no_suggest" -trimpath -ldflags="-s -w" -o myapp ./cmd/myapp
+```
+
+## Transition to v3
+
+These build tags are not present in `urfave/cli/v3` because v3 decouples these features by design:
+
+- Documentation generation lives in the separate module `github.com/urfave/cli-docs/v3`.
+- Typo suggestions use an internal Jaro-Winkler implementation with no external dependencies.
+- v3 provides the `urfave_cli_no_template` build tag to restore linker dead code elimination.
+
+See the [v2 to v3 Migration Guide](migrating-to-v3.md) and [v3 Binary Size](../v3/binary-size.md)
+for details.

mkdocs.yml

@@ -48,6 +48,7 @@ nav:
       - Getting Started: v2/getting-started.md
       - Migrating to v3: v2/migrating-to-v3.md
       - Migrating From Older Releases: v2/migrating-from-older-releases.md
+      - Binary Size: v2/binary-size.md
       - Examples:
           - Greet: v2/examples/greet.md
           - Arguments: v2/examples/arguments.md