Add vector filters (#3341)

* add vector filters

* Update code samples [skip ci]

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: guimachiavelli

learn/filtering_and_sorting/filter_expression_reference.mdx

@@ -108,6 +108,19 @@ release_date NOT EXISTS
 NOT release_date EXISTS
 ```
 
+#### Vector filters
+
+When using AI-powered search, you may also use `EXISTS` to filter documents containing vector data:
+
+- `_vectors EXISTS`: matches all documents with an embedding
+- `_vectors.{embedder_name} EXISTS`: matches all documents with an embedding for the given embedder
+- `_vectors.{embedder_name}.userProvided EXISTS`: matches all documents with a user-provided embedding on the given embedder
+- `_vectors.{embedder_name}.documentTemplate EXISTS`: matches all documents with an embedding generated from a document template. Excludes user-provided embeddings
+- `_vectors.{embedder_name}.regenerate EXISTS`: matches all documents with an embedding scheduled for regeneration
+- `_vectors.{embedder_name}.fragments.{fragment_name} EXISTS`: matches all documents with an embedding generated from the given multimodal fragment. Excludes user-provided embeddings
+
+`_vectors` is only compatible with the `EXISTS` operator.
+
 ### `IS EMPTY`
 
 The `IS EMPTY` operator selects documents in which the specified attribute exists but contains empty values. The following expression only returns documents with an empty `overview` field:

learn/resources/telemetry.mdx

@@ -147,6 +147,7 @@ This list is liable to change with every new version of Meilisearch. It's not be
 | `filter.with_geoBoundingBox`                       | `true` if the filter rule `_geoBoundingBox` is specified                                    | false
 | `filter.with_geoRadius`                            | `true` if the filter rule `_geoRadius` is specified                                         | false
 | `filter.most_used_syntax`                          | Most used filter syntax among all search requests containing the `filter` parameter         | string
+| `filter.on_vectors`                            | `true` if the filter rule includes `_vector`                                         | false
 | `q.max_terms_number`                               | Highest number of terms given for the `q` parameter                                         | 5
 | `pagination.max_limit`                             | Highest value given for the `limit` parameter                                               | 60
 | `pagination.max_offset`                            | Highest value given for the `offset` parameter                                              | 1000
@@ -273,3 +274,4 @@ This list is liable to change with every new version of Meilisearch. It's not be
 | `export.avg_payload_size`            | Average payload size per export                                  | `512`
 | `webhooks_created`                   | Number of webhooks created in an instance                                  | `2`
 | `webhooks.updated`                   | Number of times all webhooks in an instance have been updated                                  | `5`
+| `with_vector_filter`                   | `true` when a document fetch request used a vector filter                                  | `false`