expose the embedded OpenLayers lib (for template=openlayers) in a new /extra folder (#1002)

Author: jmckenna

conf.py

@@ -157,6 +157,12 @@ def __getattr__(cls, name):
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ['_static']
 
+# Add paths that you wish to copy to the output directory
+# see: https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-html_extra_path
+# note that the actual 'extra' folder itself is excluded, so only its contents
+# are copied to the output directory
+html_extra_path = ['./extra']
+
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
 html_last_updated_fmt = '%Y-%m-%d'

en/cgi/openlayers.txt

@@ -100,3 +100,15 @@ Customizing settings
 * environment variables::
 
     MS_OPENLAYERS_JS_URL - The URL to the OpenLayers javascript library. Per default the library loaded from the MapServer web server.
+
+Location of the embedded OpenLayers.js file
+-------------------------------------------
+
+If you aren't providing your own OpenLayers library through `MS_OPENLAYERS_JS_URL`, 
+MapServer will point to a hardcoded filepath of `www.mapserver.org/lib` to find the OpenLayers 
+library, referred to in [maptemplate.c](https://github.com/MapServer/MapServer/blob/main/src/maptemplate.c#L54).
+
+The contents on that `lib` folder is stored in the MapServer documentation repository, 
+in the [/extra](https://github.com/MapServer/MapServer-documentation/tree/main/extra) folder.
+You are warmly encouraged to contribute to upgrading the OpenLayers library, at any time (maybe start 
+with creating a new [Pull Request](https://github.com/MapServer/MapServer-documentation/pulls) there.