Docs - what-is-porter.md update

[phillipgibson]

          Reading this sentence makes me really not like the `s/invocation images/bundle installers/` I just did - if we can come up with a better name I'm down tho

Originally posted by @schristoff in #2790 (comment)

[kelvinparmar]

Hey @phillipgibson I want to contribute in this project can you help me how can I?

[sbshah97]

Hi @schristoff didn't really get what you meant down here? Any chance you could help ?

[schristoff]

Hi @sbshah97 and @kelvinparmar ! This was a note I left while we were moving our documentation around for us in the future to use when revisiting our docs. I would reference this issue #2798 - and if you'd like to contribute I would encourage you to come hang out at our community meetings that are Thursday (there's one 2/8) at 9AM MST. :) Happy to answer any other questions.