Add markdown linting support

manuscript/recipes/gollum.md

@@ -16,7 +16,6 @@ Gollum pages:
 * Can be edited with your favourite system editor or IDE (_changes will be visible after committing_) or with the built-in web interface.
 * Can be displayed in all versions (_commits_).
 
-
 ![Gollum Screenshot](../images/gollum.png)
 
 As you'll note in the (_real world_) screenshot above, my requirements for a personal wiki are:
@@ -40,7 +39,7 @@ Gollum meets all these requirements, and as an added bonus, is extremely fast an
 
 We'll need an empty git repository in /var/data/gollum for our data:
 
-```
+```bash
 mkdir /var/data/gollum
 cd /var/data/gollum
 git init
@@ -51,7 +50,7 @@ git init
 1. Choose an oauth provider, and obtain a client ID and secret
 2. Create gollum.env, and populate with the following variables (_you can make the cookie secret whatever you like_)
 
-```
+```bash
 OAUTH2_PROXY_CLIENT_ID=
 OAUTH2_PROXY_CLIENT_SECRET=
 OAUTH2_PROXY_COOKIE_SECRET=
@@ -122,4 +121,4 @@ Authenticate against your OAuth provider, and then start editing your wiki!
 
 [^1]: In the current implementation, Gollum is a "single user" tool only. The contents of the wiki are saved as markdown files under /var/data/gollum, and all the git commits are currently "Anonymous"
 
---8<-- "recipe-footer.md"
+--8<-- "recipe-footer.md"