Added a section of Update parent POM page

[pyther-hub]

This is with respect to #6109 I have followed the discussion of https://github.com/jenkins-infra/jenkins.io/pull/6113 and made the changes the code that I have added is somewhat similar to the above pull request but i have made the final changes suggested by @MarkEWaite

[pyther-hub]

I have done the required changes

[pyther-hub]

Okay as Mark stated he is busy for sometime so when he would have time to look at this then further changes can be done in the mean time @kmartens27 I have done all the formatting and labeling changes if there is something more please do let me know.

[pyther-hub]

@MarkEWaite if possible for you please have a look to this

[MarkEWaite]

@pyther-hub thanks very much for the pull request. I realized that there were additional places that used the same information, so I extracted the duplicated information to a single location and then referenced the single location in the two places where it is used.

While reading the other pages in the "Improve a plugin" tutorial, I found several places where the original tutorial missed a step to instruct the contributor to compile the plugin before submitting a pull request. I've extended your pull request to fix that mistake that I made while creating the tutorial originally.

If you'd rather that I split it into a separate pull request, let me know and I'll remove it from this pull request.

@kmartens27 could you review it one more time?

[MarkEWaite]

Thanks again @pyther-hub ! Merging