Add REPL documentation to the Gatsby Docs

[n8finch]

Description

Currently [WIP], this PR creates documentation for the Gatsby CLI REPL shell. This was merged in #7262, but didn't include documentation.

I've labeled this [WIP] because I'd like feedback on the format and content of the documentation:

1. Are the explanations clear?
2. Are the examples helpful?

I just want to make sure 🤓.

Once I get feedback, I'll finish up the docs for a merge.

Also, it looks like the dataPaths command is throwing an error? But I'll double check on that and file a bug issue (and hopefully a PR to fix it!) after the docs.

Related Issues

Fixes #7484

[lannonbr]

Thanks for the work so far @n8finch! Just a thing to do is since you are fleshing out this stub, I would recommend removing the asterisk for the gatsby-repl entry in the sidebar as it is no longer going to be a stub. It can be found in the sidebar yaml file located in www/src/data/sidebars/doc-links.yaml. Here's the file in the master branch: https://github.com/gatsbyjs/gatsby/blob/master/www/src/data/sidebars/doc-links.yaml

[n8finch]

@lannonbr thanks for the heads up, I'd completely missed that! 👍

[n8finch]

Hmm, I'm showing some CircleCI tests failing... When I look at the details, I'm not sure what went wrong. Do I need to run gatsby build to compile in the yaml updates?

[lannonbr]

Hmm, I'm showing some CircleCI tests failing... When I look at the details, I'm not sure what went wrong. Do I need to run gatsby build to compile in the yaml updates?

So there's 502 bad gateway errors coming up. Cloudflare is having some outages today and NPM is affected by such, so it's no issue on your end

[gillkyle]

I know you mentioned this is still a WIP PR but I think it's looking great! I'd never used the REPL before this but I think you give good examples.

I made a couple little suggestions, really appreciate your work on this @n8finch!

[n8finch]

Hey @gillkyle, thanks for the review and the corrections! I've never been the best speller 😂.

I've pushed up a new commit now with those changes.

I've also removed the WIP and added more documentation here.

It looks like there might be some tests failing, which I'm not sure how to resolve. Any pointers?

Thanks again!

[gillkyle]

Awesome! Thanks @n8finch! Those additional updates look awesome 😄

As far as tests go, it looks like CircleCI is complaining about linting, I think the command from this doc might be enough:

npm run format

and then push the changes. Seems like the offending file is docs/docs/gatsby-repl.md.

I've seen the windows tests just kind of fail for no real obvious reason, so pushing some change might just be enough for them to run again and maybe work. Might have to look into those more if they keep failing.

[n8finch]

@gillkyle Woohoo! That worked... Hahaha.. Machines... Thanks!

[gillkyle]

Thanks so much @n8finch! Appreciate you iterating on this several times to get everything really solid 😄

[n8finch]

Thanks for your help @gillkyle , @lannonbr , and @muescha ! I learned a lot!