add type docu to changelog template

changelog/README.md

@@ -4,3 +4,13 @@ We are using [calens](https://github.com/restic/calens) to properly generate a
 changelog before we are tagging a new release. To get an idea how this could
 look like <https://github.com/restic/restic/tree/master/changelog> would be the
 best reference.
+
+## Create changelog items
+
+Create a file according to the template for each changelog in the unreleased folder. 
+The following change types are possible: 
+- Bugfix (general Bugfix)
+- Enhancement (new feature)
+- Change (breaking change) 
+- Security (security related issues)
+

changelog/TEMPLATE

@@ -9,3 +9,7 @@ in case there aren't any issue links) is used as the primary ID.
 
 https://github.com/owncloud/ocis/pull/55555
 https://github.com/owncloud/ocis/issues/1234
+
+Note: Possible keywords are Bugfixes (for bug fixes), Enhancement (for new features),
+Change (for breaking changes), Security (for security related topics)
+

changelog/unreleased/reva-gateway-configuration.md

@@ -1,7 +1,8 @@
-Enhancement: Unify Envvar names configuring REVA gateway address
+Change: Unify Envvar names configuring REVA gateway address
 
 We've renamed all envvars configuring REVA gateway address to `REVA_GATEWAY`, 
 additionally we renamed the cli parameters to `--reva-gateway-addr` and adjusted the description
 
 https://github.com/owncloud/ocis/pull/2587
 https://github.com/owncloud/ocis/issues/2091
+