docs: improve version variable documentation in main.go

Enhanced the comment for the version variable to better explain:
- How the version is set via ldflags during build
- The exact ldflag format used (-X main.version=<version>)
- That "dev" is the default for local development builds

This makes it clearer for contributors how the version system works.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: Brandon Honeycutt

cmd/hosts-manager/main.go

@@ -20,7 +20,9 @@ var (
 	cfg     *config.Config
 	verbose bool
 	dryRun  bool
-	version = "dev" // Will be overridden by ldflags during build
+	// version is set via ldflags during build: -X main.version=<version>
+	// Defaults to "dev" for local development builds
+	version = "dev"
 )
 
 func main() {