Do not ignore 'custom_edit_url'

[stevenzeck]

Motivation

Receiving header field 'custom_edit_url' is not supported in terminal

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

• Add custom_edit_url to any `.md' file
• Start server and verify you receive the not supported message
• Add custom_edit_url into readMetadata.js
• Start server again and verify that that message is no longer reported in terminal
• Regress

Related PRs

None

[facebook-github-bot]

Thank you for your pull request and welcome to our community. We require contributors to sign our Contributor License Agreement, and we don't seem to have you on file. In order for us to review and merge your code, please sign up at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need the corporate CLA signed.

If you have received this in error or have any questions, please contact us at cla@fb.com. Thanks!

[stevenzeck]

I have signed the CLA now. Thanks!

[facebook-github-bot]

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Facebook open source project. Thanks!

[yangshun]

Many thanks! 🎉

[stevenzeck]

@yangshun it looks like with this original commit ad5b8b9 it completely ignores headings if they're not supported, shouldn't it be throwing an error since it's a breaking change?

[yangshun]

@szeck87 It's not a breaking change if only supported fields were used. In this case, it was our bug that we didn't update the supported header fields with the full set. I'll do an audit on them.