docs: apply boosts and tag a few things (#4455)

Manual pass to apply a few heuristics:

* Boost conceptual pages
* Deboost (is that a word?) index pages that list all content
* Prefer Agents pages if search query contains the word "agent"
* Add tags for a few selected pages

docs/docs/agents/models.md

@@ -1,3 +1,14 @@
+---
+search:
+  boost: 2
+tags:
+  - anthropic
+  - openai
+  - agent
+hide:
+  - tags
+---
+
 # Models
 
 This page describes how to configure the chat model used by an agent.
@@ -66,4 +77,4 @@ agent = create_react_agent(
 ## Additional resources
 
 - [Model integration directory](https://python.langchain.com/docs/integrations/chat/)
-- [Universal initialization with `init_chat_model`](https://python.langchain.com/docs/how_to/chat_models_universal_init/)
+- [Universal initialization with `init_chat_model`](https://python.langchain.com/docs/how_to/chat_models_universal_init/)