Fix broken default "Edit this page" URL

[SafraNako]

Problem

docusaurus.config.js sets the docs plugin's default editUrl to:

editUrl: 'https://github.com/theqrl.org/documentation',

That treats the docs site's custom domain (theqrl.org) as if it were a
GitHub org/user name, giving github.com/theqrl.org/documentation —
which 404s:

$ curl -o /dev/null -w '%{http_code}\n' https://github.com/theqrl.org/documentation
404

Fix

The GitHub org is theQRL (github.com/theQRL/documentation), and
Docusaurus's editUrl convention for the docs plugin is the folder
containing docs/ with /edit/<branch>/ appended — it appends each
page's own relative path under docs/ automatically:

editUrl: 'https://github.com/theQRL/documentation/edit/main/',

$ curl -o /dev/null -w '%{http_code}\n' \
    https://github.com/theQRL/documentation/edit/main/docs/getting-started.md
302   # redirects to GitHub login, i.e. the route exists

Scope

Almost every page in docs/ already sets its own custom_edit_url in
frontmatter, which overrides this default — so today only one page
(docs/Use/Tools/ems/_emsInfo.md, a partial) is directly affected. But
it's the default every future page inherits unless a contributor
remembers to add the override, so it's worth having correct.

Verification

npm run build (the site has onBrokenLinks: 'throw') completes clean:

✔ Client: Compiled successfully
✔ Server: Compiled successfully
[SUCCESS] Generated static files in "build".

🤖 Generated with Claude Code

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