remove not working plugins

Author: topi314

docs/plugins.md

@@ -18,7 +18,6 @@ for instructions.
 | [LavaSrc plugin](https://github.com/topi314/LavaSrc)                      | Spotify, Apple Music & Deezer(native play) support                                                     |
 | [LavaSearch plugin](https://github.com/topi314/LavaSearch)                | Advanced search functionality including playlists, albums, artists, tracks & terms                     |
 | [DuncteBot plugin](https://github.com/DuncteBot/skybot-lavalink-plugin)   | Additional source managers that are not widely used                                                    |
-| [Extra Filter plugin](https://github.com/rohank05/lavalink-filter-plugin) | Additional audio filters for lavalink                                                                  |
 | [XM plugin](https://github.com/esmBot/lava-xm-plugin)                     | Support for various [music tracker module](https://en.wikipedia.org/wiki/Module_file) formats          |
 | [Lyrics.kt plugin](https://github.com/DRSchlaubi/lyrics.kt)               | Plugin that fetches timestamped lyrics from YouTube                                                    |
 | [Java Timed Lyrics](https://github.com/DuncteBot/java-timed-lyrics)       | Timestamped lyrics from YouTube with Genius fallback, supports IP-rotation                             |