Fix Link and Comment in Pull Template

Author: konstantinullrich

.github/pull_request_template.md

@@ -1,11 +1,11 @@
 # Pull Request Checklist 
 
 * [ ] My commits are in nice logical chunks with [good commit messages](http://chris.beams.io/posts/git-commit/)
-* [ ] My changes are [rebased](https://medium.freecodecamp.org/git-rebase-and-the-golden-rule-explained-70715eccc372) on the latest [`trunk`](https://github.com/konstantinullrich/crypton/tree/trunk) branch
+* [ ] My changes are [rebased](http://blog.axosoft.com/golden-rule-of-rebasing-in-git/) on the latest [`trunk`](https://github.com/konstantinullrich/crypton/tree/trunk) branch
 * [ ] Ran ´dartfmt -w lib test example´
 * [ ] All tests are passing
 * [ ] My changes are ready to be shipped to users
 
 
 ## Issues affected
-<!-- Use 'Fixes #1' for Bug fixes and 'Closes #1' for every other issue affected--!>
+<!-- Use 'Fixes #1' for Bug fixes and 'Closes #1' for every other issue affected -->