docs: add versions panel

docs/assets/versions.css

@@ -0,0 +1,19 @@
+.rst-other-versions {
+    text-align: right;
+}
+
+.rst-other-versions > dl, .rst-other-versions dt, .rst-other-versions small {
+    display: none;
+}
+
+.rst-other-versions > dl:first-child {
+    display: block;
+}
+
+.rst-versions.shift-up .rst-other-versions {
+    display: block;
+}
+
+.rst-versions .rst-other-versions {
+    display: none;
+}

docs/assets/versions.js

@@ -0,0 +1,22 @@
+function callback(response) {
+    const div = document.createElement('div');
+    div.innerHTML = response.html;
+    document.body.appendChild(div);
+    const container = div.querySelector('.rst-versions');
+    div.querySelector('.rst-current-version').addEventListener('click', function() {
+        const classes = container.className.split(' ');
+        const index = classes.indexOf('shift-up');
+        if (index === -1) {
+            classes.push('shift-up');
+        } else {
+            classes.splice(index, 1);
+        }
+        container.className = classes.join(' ');
+    });
+}
+
+var script = document.createElement('script');
+script.src = 'https://argocd-notifications.readthedocs.io/_/api/v2/footer_html/?'+
+    'callback=callback&project=argocd-notifications&page=&theme=mkdocs&format=jsonp&docroot=docs&source_suffix=.md&version=' + (window['READTHEDOCS_DATA'] || { version: 'latest' }).version;
+
+document.getElementsByTagName('head')[0].appendChild(script);

mkdocs.yml

@@ -12,6 +12,10 @@ theme:
   font:
     text: 'Work Sans'
   logo: 'assets/logo.png'
+extra_javascript:
+  - assets/versions.js
+extra_css:
+  - assets/versions.css
 markdown_extensions:
 - codehilite
 - admonition