[danger] add more checks

Dangerfile

@@ -8,6 +8,17 @@ warn("PR is classed as Work in Progress") if github.pr_title.include? "[WIP]"
 # Warn when there is a big PR
 warn("Big PR") if git.lines_of_code > 500
 
-# Don't let testing shortcuts get into master by accident
-fail("fdescribe left in tests") if `grep -r fdescribe specs/ `.length > 1
-fail("fit left in tests") if `grep -r fit specs/ `.length > 1
+has_app_changes = git.modified_files.grep(%{apicast/})
+markdown_files = git.modified_files.grep(/\.md$/)
+
+if !git.modified_files.include?("CHANGELOG.md") && has_app_changes
+  fail("Please include a CHANGELOG entry. \nYou can find it at [CHANGELOG.md](https://github.com/3scale/apicast/blob/master/CHANGELOG.md).")
+  message "Note, we hard-wrap at 80 chars and use 2 spaces after the last line."
+end
+
+ENV['LANG'] = 'en_US.utf8'
+prose.lint_files markdown_files - %w(CHANGELOG.md)
+
+# Look for spelling issues
+prose.ignored_words = %w(s2i openresty APIcast nameservers resty-resolver nginx Redis OAuth ENV backend)
+prose.check_spelling markdown_files - %w(CHANGELOG.md)