[Docs] Relocate bbq.md from index-settigns (elastic#139441)

Move 'bbq.md' from 'index-settings' to 'mapping-reference' folder.
Update 'toc.yml' to reflect the new file location.
Add and correct link to 'bbq.md' in 'dense-vector.md' for consistency.

Author: mayya-sharipova

docs/redirects.yml

@@ -1,4 +1,7 @@
 redirects:
+  # Redirect for bbq.md move
+  'reference/elasticsearch/index-settings/bbq.md': 'reference/elasticsearch/mapping-reference/bbq.md'
+
   # Related to https://github.com/elastic/elasticsearch/pull/130716/
   'reference/query-languages/eql/eql-ex-threat-detection.md': 'docs-content://explore-analyze/query-filter/languages/example-detect-threats-with-eql.md'
 

…ence/elasticsearch/index-settings/bbq.md …e/elasticsearch/mapping-reference/bbq.mddocs/reference/elasticsearch/index-settings/bbq.md renamed to docs/reference/elasticsearch/mapping-reference/bbq.md docs/reference/elasticsearch/index-settings/bbq.md renamed to docs/reference/elasticsearch/mapping-reference/bbq.md

@@ -192,7 +192,7 @@ The `dense_vector` type supports quantization to reduce the memory footprint req
 
 * `int8` - Quantizes each dimension of the vector to 1-byte integers. This reduces the memory footprint by 75% (or 4x) at the cost of some accuracy.
 * `int4` - Quantizes each dimension of the vector to half-byte integers. This reduces the memory footprint by 87% (or 8x) at the cost of accuracy.
-* `bbq` - Better binary quantization which reduces each dimension to a single bit precision. This reduces the memory footprint by 96% (or 32x) at a larger cost of accuracy. Generally, oversampling during query time and reranking can help mitigate the accuracy loss.
+* `bbq` - [Better binary quantization](/reference/elasticsearch/mapping-reference/bbq.md) which reduces each dimension to a single bit precision. This reduces the memory footprint by 96% (or 32x) at a larger cost of accuracy. Generally, oversampling during query time and reranking can help mitigate the accuracy loss.
 
 When using a quantized format, you may want to oversample and rescore the results to improve accuracy. See [oversampling and rescoring](docs-content://solutions/search/vector/knn.md#dense-vector-knn-search-rescoring) for more information.
 

docs/reference/elasticsearch/mapping-reference/dense-vector.md

@@ -38,7 +38,6 @@ toc:
   - file: index-settings/index.md
     children:
         - file: index-settings/serverless.md
-        - file: index-settings/bbq.md
         - file: index-settings/index-modules.md
         - file: index-settings/shard-allocation.md
           children:
@@ -219,6 +218,7 @@ toc:
           - file: mapping-reference/mapping-store.md
           - file: mapping-reference/subobjects.md
           - file: mapping-reference/term-vector.md
+          - file: mapping-reference/bbq.md
   - file: elasticsearch-audit-events.md
   - file: command-line-tools/index.md
     children: