Update Nginx reverse proxy documentation to include support for unix domain sockets

[kmartens27]

Describe your use-case which is not covered by existing documentation.

As a result of merging this packaging pull request, Jenkins now supports Unix domain sockets.

The various reverse proxy configuration pages need to be updated accordingly to include this new information. This ticket is for the Nginx reverse proxy specifically, as other configurations will have their own tickets.

Reference any relevant documentation, other materials or issues/pull requests that can be used for inspiration.

No response

[yashisrani]

please assign me this issue ... @kmartens27

[zbynek]

@yashisrani issues in this repository are not assigned, you're welcome to work on it.

[kmartens27]

Hi @yashisrani, as @zbynek shared, we do not assign issues in the jenkins.io repo. If you want to work on the issue, submitting a comment here stating that you are working on it is more than enough. Our contributing guide goes into more detail about expectations around contributing if you have any additional questions.