Let every documentation format report

The matrix cancels the other two formats as soon as one fails, so a html
build that stops partway through the examples takes latex and epub with
it and there is nothing to compare it against. python_package.yaml
already sets fail-fast: false for the same reason.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: kip-hart

.github/workflows/documentation.yaml

@@ -10,6 +10,10 @@ jobs:
   docs-checks:
     name: ${{ matrix.doc-type }}
     strategy:
+      # Let every format report. Without this, one failing format cancels
+      # the other two, and a build that fails partway through the examples
+      # takes the evidence of the others with it.
+      fail-fast: false
       matrix:
         doc-type: [html, latex, epub]