Implement searching wiki link under project root

[syohex]

Description

#591 (comment)

Related Issue

Type of Change

• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING.md document.
• I have updated the documentation in the README.md file if necessary.
• I have added an entry to CHANGES.md.
• I have added tests to cover my changes.
• All new and existing tests passed (using make test).

[syohex]

All tests are passed with latest emacs on my local environment.

[srid]

While this works with project.el (as confirmed here), I noticed that the experience is a bit jarring on doom-emacs. This is not markdown-mode's fault, because doom-emacs uses projectile and not project.el, which is perhaps why C-c C-o is repeatedly prompting me to specify the project root, rejecting what I give it most times, and then not remembering it for the rest of the session. I've asked in the Doom-Emacs discord channel asking how to best approach this problem; here's the permalink to that question.

[srid]

Actually, nevermind ... upgrading project.el resolves this issue. I only had to put this in doom-emacs's packages.el file.

(package! project)

[syohex]

I have committed a43629d. It let us not load project.el if project is managed by VCS system such as git.

And all tests are passed on all emacs version. Emacs 28 or higher versions requires ~/.emacs.d/projects directory for using project.el functions. That directory does not exists on CI environment so tests were failed on Emacs 28.