Fix caps to expected caps for LangChain provider (and to match docs)

[sfc-gh-jreini]

Description

Fix caps to expected caps for LangChain provider (and to match docs). Identified in https://github.com/truera/trulens/issues/1454

Other details good to know for developers

Please include any other details of this change useful for TruLens developers.

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] New Tests
• [x] This change includes re-generated golden test results
• [x] This change requires a documentation update

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