Simplify repoRootPath option

[colebemis]

Problem

We currently require users to specify a repoRootPath option in gatsby-config.js in order to generate GitHub edit links for each page. repoRootPath is the absolute path to the root of the users git repository. Since the path needs to be absolute, users have to use Node.js functions like process.cwd() and path.resolve() to compute the path. This can be confusing for less technical users.

Solution

I simplified repoRootPath so it now accepts a relative path instead of an absolute path. I also set the default repoRootPath to '.'.

repoRootPath can accept a relative path because the current working directory when executing gatsby-node.js is the root of the user's Gatsby site. So we can use process.cwd() and path.resolve() in gatsby-node.js to compute the absolute path to the root of their git repository given a relative path.

Impact

If a user's site is located at the root of their git repository, they won't have to specify repoRootPath. If their site is in a subdirectory, they can specify the relative path to the root with a string instead of using process.cwd() and path.resolve().

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[emplums]

Awesome, this experience is much better! 🙌