Revert "cacheGroups" (#2725)

* Revert "docs(plugins): Add title to cacheGroups (#2227)"

This reverts commit 5b3906e.

Author: EugeneHlushko

src/content/plugins/split-chunks-plugin.md

@@ -217,8 +217,6 @@ A module can belong to multiple cache groups. The optimization will prefer the c
 
 If the current chunk contains modules already split out from the main bundle, it will be reused instead of a new one being generated. This can impact the resulting file name of the chunk.
 
-#### `splitChunks.cacheGroups.cacheGroup.test`
-
 __webpack.config.js__
 
 ```js