Merge branch '41601-document-pages-static-gzip' into 'master'

Resolve "I wonder how to leverage browser caching of my Gitlab pages?"

Closes #15037

See merge request gitlab-org/gitlab-ce!16829

doc/user/project/pages/introduction.md

@@ -316,6 +316,47 @@ or various static site generators. Contributions are very welcome.
 Visit the GitLab Pages group for a full list of example projects:
 <https://gitlab.com/groups/pages>.
 
+### Serving compressed assets
+
+Most modern browsers support downloading files in a compressed format. This
+speeds up downloads by reducing the size of files.
+
+Before serving an uncompressed file, Pages will check whether the same file
+exists with a `.gz` extension. If it does, and the browser supports receiving
+compressed files, it will serve that version instead of the uncompressed one.
+
+To take advantage of this feature, the artifact you upload to the Pages should
+have this structure:
+
+```
+public/
+├─┬ index.html
+│ └ index.html.gz
+│
+├── css/
+│   └─┬ main.css
+│     └ main.css.gz
+│
+└── js/
+    └─┬ main.js
+      └ main.js.gz
+```
+
+This can be achieved by including a `script:` command like this in your
+`.gitlab-ci.yml` pages job:
+
+```yaml
+pages:
+  # Other directives
+  script:
+    - # build the public/ directory first
+    - find public -type f -iregex '.*\.\(htm\|html\|txt\|text\|js\|css\)$' -execdir gzip -f --keep {} \;
+```
+
+By pre-compressing the files and including both versions in the artifact, Pages
+can serve requests for both compressed and uncompressed content without
+needing to compress files on-demand.
+
 ### Add a custom domain to your Pages website
 
 For a complete guide on Pages domains, read through the article