Fix bump tool

tools/bump.sh

@@ -1,16 +1,23 @@
 #!/usr/bin/env bash
 #
-# 1. Bump latest version number to files:
-#   - _sass/jekyll-theme-chirpy.scss
-#   - assets/js/.copyright.js
-#   - assets/js/dist/*.js (will be built by gulp later)
-#   - jekyll-theme-chirpy.gemspec
-#   - Gemfile.lock
-#   - package.json
+# How does it work:
 #
-# 2. Create a git-tag on release branch
+#   1. Bump latest version number to files:
+#     - _sass/jekyll-theme-chirpy.scss
+#     - assets/js/_copyright.js
+#     - assets/js/dist/*.js (will be built by gulp later)
+#     - jekyll-theme-chirpy.gemspec
+#     - package.json
 #
-# 3. Build a RubyGems package base on the latest git-tag
+#   2. Create a git-tag on release branch
+#
+#   3. Build a RubyGems package base on the latest git-tag
+#
+#
+# Usage:
+#
+#   Switch to 'master' branch or 'X-Y-stable' branch with argument '-m',
+#`  and then run this script.
 #
 #
 # Requires: Git, Gulp, RubyGems
@@ -41,9 +48,9 @@ check() {
     exit -1
   fi
 
-  # ensure the current branch is 'master'
-  if [[ "$(git branch --show-current)" != "master" && manual_release == "false" ]]; then
-    echo "Error: This operation must be performed on the 'master' branch!"
+  # ensure the current branch is 'master' or running in 'manual' mode
+  if [[ "$(git branch --show-current)" != "master" && $manual_release == "false" ]]; then
+    echo "Error: This operation must be performed on the 'master' branch or '--manual' mode!"
     exit -1
   fi