Added results from usage research

ba-usage.md

@@ -0,0 +1,31 @@
+This is what I wanted the usage command to return:
+```
+Usage:
+  bundle-audit [COMMAND] [OPTIONS]
+
+Commands:
+  check, -c [DIR]     # Scan Gemfile.lock for insecure dependencies.
+  update, -u          # Update the ruby-advisory-db.
+  version             # Prints the bundler-audit version.
+  help, -h [COMMAND]  # Describe available commands or one specific command.
+  download            # Downloads ruby-advisory-db.
+  stats               # Prints ruby-advisory-db stats.
+  tree                # Print a tree of all available commands.
+
+Options for `check`:
+  --update, -u        # Update ruby-advisory-db before scanning.
+  --no-update         # Do not update the advisory database.
+  --verbose, -v       # Show full advisory details.
+  --quiet, -q         # Suppress normal output (exit codes only).
+  --ignore FILE       # Ignore one or more advisory IDs (repeatable).
+  --only FILE         # Only check the specified advisory IDs.
+  --gemfile PATH      # Use a specific Gemfile.lock.
+  --format FORMAT     # Output format: text (default), json, yaml
+
+Examples:
+  bundle-audit check
+  bundle-audit check --verbose
+  bundle-audit check --ignore CVE-2020-1234
+  bundle-audit check --format json > audit.json
+  bundle-audit update
+```