Improving TruLens evaluation Documentation

[Moeinmn]

Checked

• I searched existing ideas and did not find a similar one
• I added a very descriptive title
• I've clearly described the feature request and motivation for it

Feature request

Recently, I tried to evaluate my application. After reading LangChain and TruLens documentation, I realized that there are some absolutely useful techniques like the Rag Triad. It was well-written in the TruLens documentation but was missing in the LangChain docs. I would love to see this documentation in LangChain docs

Trulens Docs
Langchain Trulenz Docs

Motivation

I want to add Rag Triad info to LangChain docs because it's missing but helpful.

Proposal (If applicable)

No response