Remove broken documentation links (#10426)

Description: Removed some broken links for popular chains and
additional/advanced chains.
Issue: None
Dependencies: None
Tag maintainer: none yet
Twitter handle: ferrants 

Alternatively, these pages could be created, there are snippets for the
popular pages, but no popular page itself.

docs/docs_skeleton/docs/modules/chains/index.mdx

@@ -19,8 +19,6 @@ For more specifics check out:
 - [How-to](/docs/modules/chains/how_to/) for walkthroughs of different chain features
 - [Foundational](/docs/modules/chains/foundational/) to get acquainted with core building block chains
 - [Document](/docs/modules/chains/document/) to learn how to incorporate documents into chains
-- [Popular](/docs/modules/chains/popular/) chains for the most common use cases
-- [Additional](/docs/modules/chains/additional/) to see some of the more advanced chains and integrations that you can use out of the box
 
 ## Why do we need chains?