Policy templates for Firefox 116 and Firefox ESR 115.1

Note: There are no changes to the ADMX templates in this release. I bumped the version to be consistent. There is no need to move to these templates if you are using v5.0.

Note: While these templates will work for Firefox ESR 91, they contain new policies that are not in Firefox ESR 91. If you need to manage Firefox ESR 91, you should use v3.10

The README that corresponds to this release is:

https://github.com/mozilla/policy-templates/blob/v5.1/docs/index.md

This release contains fixes to the German translation thanks to @vossni and @MaikLHD.