Docs for the cast integration (#172)

* Added cast integration docs.

* Changed header sizes.

* Added more space above Requirements

* Added cast integration docs.

* Removed separate cast integration docs

* Further indented quote from Google

docs/Settings.md

@@ -36,7 +36,17 @@ Additional settings passed to yt-dlp.
 All third party integrations of TubeArchivist will **always** be *opt in*.
 - **API**: Your access token for the Tube Archivist API. 
 - **returnyoutubedislike.com**: This will get return dislikes and average ratings for each video by integrating with the API from [returnyoutubedislike.com](https://www.returnyoutubedislike.com/).
-- **Cast**: Enable Google Cast for videos. Requires a valid SSL certificate and works only in Google Chrome.
+- **Cast**: Enabling the cast integration in the settings page will load an additional JS library from **Google**.
+    * Requirements
+        - HTTPS
+            * To use the cast integration HTTPS needs to be enabled, which can be done using a reverse proxy. This is a requirement by Google as communication to the cast device is required to be encrypted, but the content itself is not.
+        - Supported Browser
+            * A supported browser is required for this integration such as Google Chrome. Other browsers, especially Chromium-based browsers, may support casting by enabling it in the settings.
+        - Subtitles
+            * Subtitles are supported however they do not work out of the box and require additional configuration. Due to requirements by Google, to use subtitles you need additional headers which will need to be configured in your reverse proxy. See this [page](https://developers.google.com/cast/docs/web_sender/advanced#cors_requirements) for the specific requirements.
+               > You need the following headers: Content-Type, Accept-Encoding, and Range. Note that the last two headers, Accept-Encoding and Range, are additional headers that you may not have needed previously.
+               > Wildcards "*" cannot be used for the Access-Control-Allow-Origin header. If the page has protected media content, it must use a domain instead of a wildcard.
+
 
 # Scheduler Setup
 Schedule settings expect a cron like format, where the first value is minute, second is hour and third is day of the week. Day 0 is Sunday, day 1 is Monday etc.