DOCS: partners/chroma: Fix documentation around chroma query filter syntax

[hesreallyhim]

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Description:

• Starting to put together some PR's to fix the typing around langchain-chroma filter and where_document query filtering, as mentioned:

#30879
#30507

The typing of dict[str, str] is on the one hand too restrictive (marks valid filter expressions as ill-typed) and also too permissive (allows illegal filter expressions). That's not what this PR addresses though. This PR just removes from the documentation some examples of filters that are illegal, and also syntactically incorrect: (a) dictionaries with keys like $contains but the key is missing quotation marks; (b) dictionaries with multiple entries - this is illegal in Chroma filter syntax and will raise an exception. ({"foo": "bar", "qux": "baz"}). Filter dictionaries in Chroma must have one and one key only. Again this is just the documentation issue, which is the lowest hanging fruit. I also think we need to update the types for filter and where_document to be (at the very least dict[str, Any]), or, since we have access to Chroma's types, they should be Where and WhereDocument types. This has a wider blast radius though, so I'm starting small.

This PR does not fix the issues mentioned above, it's just starting to get the ball rolling, and cleaning up the documentation.

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[hesreallyhim]

Thanks @ccurme .... I was going to follow up on this by changing the types for the chroma filter from dict[str, str] to the actual types, which are available through chromadb (Where and WhereDocument) because dict[str, str] is really not accurate.... what I found though, is that my IDE still couldn't validate whether a filter expression was correct or not, because Where is a nested/recursive type. One alternative is to change the type to dict[str, Any], since it seems to me like it's better to be overly permissive than overly restrictive in this case, but at the end of the day I think it's not possible to give them the right type without other strategies of validation