Added comma to fix grammar (#611)

Author: ArjhanToteck

docs/installation.md

@@ -341,7 +341,7 @@ Detailed configuration available in the [configuration guide](./configuration.md
 
 You must set a random generated value for the parameter `hmac_key:`! On Linux you can generate it using the command `pwgen 20 1`.
 
-Because of various issues Invidious **must** be restarted often, at least once a day, ideally every hour.
+Because of various issues, Invidious **must** be restarted often, at least once a day, ideally every hour.
 
 If you use a reverse proxy, you **must** configure invidious to properly serve request through it: