Explain how to add new examples to the gallery

[melissawm]

Description

Adds some explanation on how to add new examples to the gallery.

Type of change

• Fixes or improves existing content
• Adds new content page(s)
• Fixes or improves workflow, documentation build or deployment

References

Closes #92

Final checklist:

• My PR is the minimum possible work for the desired functionality
• I have commented my code, particularly in hard-to-understand areas
• I have added alt text to new images included in this PR

[psobolewskiPhD]

Awesome!

[jni]

@melissawm super great, thank you! 😊

Do you think we should also point out that napari.run() needs to be under a __main__ guard or things won't work? That won't be obvious to most users.

[jni]

Do we also want to add a note that napari.run() has to be under the __main__ guard?

[psobolewskiPhD]

Oh, yes. That's a good point I think. For people who use mostly notebooks and interactive environments the __main__ and napari.run() could be a bit of a mystery?

[melissawm]

Good point! I will explain that.

[melissawm]

Let me know if this is enough explanation - here's the relevant section: https://output.circle-artifacts.com/output/job/4f7e2cae-c069-4177-8bd7-506fe3230502/artifacts/0/docs/_build/developers/contributing.html#adding-examples-to-the-gallery

[psobolewskiPhD]

Just to be clear: when contributing an example, for the example to be in our gallery though, the main is required, right?
It's definitely required to be able to do python example.py

Also, I think ipython behaves same as jupiter, so copy paste the code just works, without the main

[melissawm]

@psobolewskiPhD you are of course right - let me know if this rephrasing reads better?

[psobolewskiPhD]

@melissawm I made some small suggestions, based on my understanding.