Update GitHub App integration overview

[yaningo]

Description

Adding content to document new trigger options for GitHub App integrated projects.

Reasons

In the additional "Run on" menu in the trigger settings, GitHub App users can now select which event will trigger the pipeline.

Content Checklist

Please follow our style when contributing to CircleCI docs. Our style guide is here: https://circleci.com/docs/style/style-guide-overview.

Please take a moment to check through the following items when submitting your PR (this is just a guide so will not be relevant for all PRs) 😸:

• Break up walls of text by adding paragraph breaks.
• Consider if the content could benefit from more structure, such as lists or tables, to make it easier to consume.
• Keep the title between 20 and 70 characters.
• Consider whether the content would benefit from more subsections (h2-h6 headings) to make it easier to consume.
• Check all headings h1-h6 are in sentence case (only first letter is capitalized).
• Is there a "Next steps" section at the end of the page giving the reader a clear path to what to read next?
• Include relevant backlinks to other CircleCI docs/pages.

[rosieyohannan]

Suggested change

	Upon xref:github-app-trigger-options/#supported-trigger-events[the event you selected under the "Run on" menu], a new pipeline is triggered. You will see the pipeline running in the CircleCI web app.
	Upon xref:github-app-trigger-options/#supported-trigger-options[the event you selected under the "Run on" menu], a new pipeline is triggered. You will see the pipeline running in the CircleCI web app.

[rosieyohannan]

Sorry I changed the tag

[yaningo]

Thanks!

[rosieyohannan]

Maybe state it's "PR opened or pushed to, default branch pushes, tag pushes"?

[rosieyohannan]

Suggested change

	In your trigger settings, select the `PR opened or pushed to, default branch pushes, tag pushes` xref:github-app-trigger-options/#supported-trigger-options[option under the "Run on" menu].
	In your trigger settings, select the "PR opened or pushed to, default branch pushes, tag pushes" option under the "Run on" menu. For a full list of GitHub App trigger options, see the xref:github-app-trigger-options/#supported-trigger-options[GitHub App trigger options] page.
	image::triggers/run-on-open.png[Run on trigger menu options]

[rosieyohannan]

We don't always follow this rule but we should generally not just link to other sections from text, the link text generally should tell you exactly what you will find when you click the link. Does that make sense?

[rosieyohannan]

https://circleci.com/docs/style/links/#cross-references

[rosieyohannan]

THis whole Trigger a pipeline in CircleCI section seems wrong now, for example "When you choose btn:[Commit and Run], as described above" ... I don't think we do describe it above anymore, could you check and see what you think? The section can probably be simplified with a link to how to trigger or something, or be condensed into the section above.

[yaningo]

I added a line in the "When you create a new organization, you will be guided to start creating projects, as follows:" bullet point list to mention the "new" Commit config and run button