Update changelog

changelog.md

 ### CHANGE LOG:
-**v2.4.5:**
+**v2.3.6:**
+- Update version
+- Use markdown in the changelog file
+- Patch for issue #1098
+- Update support emails
+- Merge pull request #1096 from nobusugi246/fix_css_content_too_large
+- min-height of .content is too large.
+
+**v2.3.5:**
 - Fix issue #1097
 - Remove changelog from readme and specify new source
 - Merge pull request #1040 from OskarStark/patch-1