[Docs] Warn latest is unstable (#101)

* docs

* docs

* docs

docs/source/_static/js/version_alert.js

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+
+function warnOnLatestVersion() {
+  if (!window.READTHEDOCS_DATA || window.READTHEDOCS_DATA.version !== "latest") {
+    return;  // not on ReadTheDocs and not latest.
+  }
+
+  var note = document.createElement('div');
+  note.setAttribute('class', 'admonition note');
+  note.innerHTML = "<p class='first admonition-title'>Note</p> " +
+    "<p> " +
+    "This documentation is for an <b>unreleased development version</b>. " +
+    "Click <a href='/en/stable'><b>here</b></a> to access the documentation of the current stable release." +
+    "</p>";
+
+  var parent = document.querySelector('#benchmarl');
+  if (parent)
+    parent.insertBefore(note, parent.querySelector('h1'));
+}
+
+document.addEventListener('DOMContentLoaded', warnOnLatestVersion);

docs/source/conf.py

@@ -41,7 +41,10 @@
 intersphinx_disabled_domains = ["std"]
 
 templates_path = ["_templates"]
-html_static_path = [osp.join(osp.dirname(benchmarl_sphinx_theme.__file__), "static")]
+html_static_path = [
+    osp.join(osp.dirname(benchmarl_sphinx_theme.__file__), "static"),
+    "_static",
+]
 
 
 html_theme = "sphinx_rtd_theme"
@@ -65,3 +68,4 @@ def rst_jinja_render(app, _, source):
         source[0] = app.builder.templates.render_string(source[0], rst_context)
 
     app.connect("source-read", rst_jinja_render)
+    app.add_js_file("js/version_alert.js")