rubocop.yml: Disable some cops locally that aren't in the styleguide

- This config applies only to this repo, it's not the global config.

.rubocop.yml

@@ -1,6 +1,33 @@
 inherit_from: ./config/default.yml
 
+AllCops:
+  SuggestExtensions: false
+
+Gemspec/RequiredRubyVersion:
+  Enabled: false
+
+Lint/AssignmentInCondition:
+  Enabled: false
+
+Lint/EmptyConditionalBody:
+  Enabled: false
+
+Lint/UselessAssignment:
+  Enabled: false
+
 Naming/FileName:
   Enabled: true
   Exclude:
     - "rubocop-github.gemspec"
+
+Style/Documentation:
+  Enabled: false
+
+Style/GuardClause:
+  Enabled: false
+
+Style/Next:
+  Enabled: false
+
+Style/SoleNestedConditional:
+  Enabled: false