Cleanup pull_request_template.md (#54)

* Update pull_request_template.md

* Removed Link to Contribution Guidelines (added by Github on the right hand side, anyhow)
* Removed Link to issue #41 from title example (this has been linked quite a lot...)

* 0.5.6

* Fix typo

Co-authored-by: Jakob Möller <jakob.moeller@sap.com>
Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>
Co-authored-by: marcmuschko <marc.muschko@sap.com>