URL
docs.sentry.io/platforms/javascript/guides/${projectName}/sourcemaps/
Additional Info
When I'm on /settings/projects/${projectName}/source-maps/ in my application, the project (which does not have source maps) has two sentences like:
"To learn more about source maps, read the docs."
My project name is, for some reason, embedded in both URLs at the spot I indicated with a variable. I think in both cases you just wanted to link to https://docs.sentry.io/platforms/javascript/sourcemaps/