Add more regex details to docs

[philipithomas]

Current page: https://docs.trychroma.com/docs/querying-collections/full-text-search#full-text-search-and-regex

Details to include:

• Limits: Must be at least 3 characters (including full-text search)
• Maximum length via quota on cloud, but no limit on single-node.
  • Update here: https://docs.trychroma.com/cloud/quotas-limits
• Uses Rust regex - look at docs for full syntax support (including - does not support lookaheads) https://docs.rs/regex/1.11.1/regex/#syntax
• Don’t support byte patterns
• Can be combined with other filters - consider a complex example with multiple filters

Additional details which we can probably skip, but adding from my notes:

• Recommend adding non-trivial substrings in regex patterns for optimal speed because it speeds up secondary scans.
• Worst case, regex scales linearly with size of collection, but avg 500ms