Secondary Side Bar deserves better documentation

[gjsjohnmurray]

Its existence is mentioned only briefly at https://code.visualstudio.com/docs/getstarted/userinterface#_basic-layout

but I didn't find information about how to move views there. Perhaps improve https://code.visualstudio.com/docs/getstarted/userinterface#_views to cover that.

[gjsjohnmurray]

Evidence at microsoft/vscode#182836 (comment)

[cadamini]

Great stuff, happy to submit the requested docs update as PR. Unfortunately, there is no preview. I hope my content/image looks good and you like my changes @gjsjohnmurray

[gregvanl]

Not sure we need to add more documentation here. Might wait to see if there are upvotes.

For how to populate the Secondary Side Bar, there is a prompt in the UX.

[gjsjohnmurray]

@sbatten I think you did a lot of the work to create the Secondary Side Bar. Do you think it is under-documented in places where new users might be reading?