Fix outdated reference from Parcels-code#2298

Author: VeckoTheGecko

docs/conf.py

@@ -47,8 +47,7 @@
 
 # The suffix(es) of source filenames.
 # You can specify multiple suffix as a list of string:
-# source_suffix = ['.rst', '.md']
-source_suffix = ".rst"
+source_suffix = [".rst", ".md"]
 
 # The encoding of source files.
 # source_encoding = 'utf-8-sig'

docs/v4/installation.md

@@ -1,6 +1,6 @@
 # Install an alpha version of Parcels v4
 
-During development of Parcels v4, we are uploading versions of the package to an [index on prefix.dev](https://prefix.dev/channels/parcels/packages/parcels). This allows users to easily install an unreleased version without having to do a [development install](../installation.rst)! Give it a spin!
+During development of Parcels v4, we are uploading versions of the package to an [index on prefix.dev](https://prefix.dev/channels/parcels/packages/parcels). This allows users to easily install an unreleased version without having to do a [development install](../installation.md)! Give it a spin!
 
 ```{warning}
 Before installing an alpha version of Parcels, we *highly* recommend creating a new environment so that doesn't affect package versions in your current environment (which you may be using for your research).