ci: verify the order of the search results

We definitely want the search results for, say, "commit" to show the
manual page of that command first.

This took quite a bit of work to accomplish, including a change to
Pagefind itself (CloudCannon/pagefind#534) as
well as some extensive fiddling with the ranking weights (including, I
kid you not, running a Powell's optimization of the weights).

To ensure that the results are shown in the desired order, let's add an
explicit check for that in the PR builds.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

.github/workflows/ci.yml

@@ -62,3 +62,17 @@ jobs:
           public/
         output: lychee.md
         jobSummary: true
+
+    - name: verify search results
+      run: |
+        set -x
+        res=0
+        for term in commit config log rev-parse
+        do
+          node ./script/run-pagefind.js "$term" | tee search.results >&2
+          grep "^1. /docs/git-$term\\.html" search.results || {
+            echo "::error::Search for $term failed to show the manual page first" >&2
+            res=1
+          }
+        done
+        exit $res