More robust handling of links directing to internal content

[abnerbog]

When merging this PR to the live page, I saw an issue with the links in the foreward TOC linking to the different book chapters. The links to the chapters redirected as expected locally and in the deploy preview, but are under the "foreward" folder in production (e.g., https://water-content-portal.cuahsi.io/foreward/plotting-demo-complete).

Also, some of the links are rendered in blue (in all environments):

and running make serve sees this warning message:

⚠️  hydroinformatics\Front_Matter\foreward.md:45 Legacy syntax used for link target, please prepend a '#' to your link url: "intro-stats-activity"

   The link target should be of the form `[](#target)`, including the `#` sign.

This may be deprecated in the future.

⚠️  hydroinformatics\Front_Matter\foreward.md:45 Linking "intro-stats-activity" to an implicit heading