exclude rake tasks and gemspec from metrics

exclude from BlockLength and LineLength metrics

.rubocop.yml

@@ -22,6 +22,8 @@ Metrics/BlockLength:
   Exclude:
     - test/**/*.rb
     - lib/jekyll/configuration.rb
+    - rake/*.rake
+    - jekyll.gemspec
 Metrics/ClassLength:
   Exclude:
     - !ruby/regexp /features\/.*.rb$/
@@ -32,6 +34,8 @@ Metrics/CyclomaticComplexity:
 Metrics/LineLength:
   Exclude:
     - !ruby/regexp /features\/.*.rb/
+    - Rakefile
+    - rake/*.rake
   Max: 90
   Severity: warning
 Metrics/MethodLength: