Document common issues with extensions / troubleshooting

[immavalls]

We've seen a couple of times recently in the forums "old" extensions that are a bit old, which work if built on their own, but hitting breaking issues when built alongside more recent extensions.

• https://community.k6.io/t/dashboard-extension-issue-with-latest-k6-version/5499/5
• https://community.k6.io/t/issue-while-installing-two-extensions-at-once/5539/5

As an initial step, it would help to document this can happen, and what users can do (open a PR, fork/contribute the code to the older extension, etc.).

[immavalls]

Another occurrence of the transitive dependencies stepping on each other https://k6io.slack.com/archives/C3E688J8Z/p1671717655815539 cc: @javaducky

[immavalls]

I thought that a section could also include:

• How to do docker (related to #920).
• How to debug an extension locally.