Improve ActionCable docs for source installs

Adds steps for source installs to configure cable.yml which is now
required since 14.5

doc/install/installation.md

@@ -578,9 +578,10 @@ sudo -u git -H git config --global core.fsyncObjectFiles true
 
 # Configure Redis connection settings
 sudo -u git -H cp config/resque.yml.example config/resque.yml
+sudo -u git -H cp config/cable.yml.example config/cable.yml
 
 # Change the Redis socket path if you are not using the default Debian / Ubuntu configuration
-sudo -u git -H editor config/resque.yml
+sudo -u git -H editor config/resque.yml config/cable.yml
 ```
 
 Make sure to edit both `gitlab.yml` and `puma.rb` to match your setup.

doc/update/upgrading_from_source.md

@@ -410,6 +410,20 @@ Example:
 Additional instructions here.
 -->
 
+### 14.5.0
+
+As part of [enabling real-time issue assignees](https://gitlab.com/gitlab-org/gitlab/-/issues/330117), Action Cable is now enabled by default, and requires `config/cable.yml` to be present.
+You can configure this by running:
+
+```shell
+cd /home/git/gitlab
+
+sudo -u git -H cp config/cable.yml.example config/cable.yml
+
+# Change the Redis socket path if you are not using the default Debian / Ubuntu configuration
+sudo -u git -H editor config/cable.yml
+```
+
 ### 13.0.1
 
 As part of [deprecating Rack Attack throttles on Omnibus GitLab](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/4750), the Rack Attack initializer on GitLab