Update markdown-link-check.json

[wesley-dean-gsa]

This adds support for the projectBaseUrl configuration directive used by markdown-link-check

[github-actions]

Thanks for the PR!

This section of the codebase is owned by @madskristensen and @hyperupcall - if they write a comment saying "LGTM" then it will be merged.

[hyperupcall]

Thanks

[wesley-dean-gsa]

Confirmed that the merge now recognizes the projectBaseUrl field:

ℹ No config file found
ℹ Processing ./.markdown-link-check.json
ℹ Found schema in https://www.schemastore.org/api/json/catalog.json ...
ℹ Validating ./.markdown-link-check.json against schema from https://json.schemastore.org/markdown-link-check.json ...
✔ ./.markdown-link-check.json is valid

Thanks for the merge. Great work, folks! I love what you're doing -- it's an incredible service!!