Make vector fields experimental feature

Relates to #33022

docs/reference/mapping/types/dense-vector.asciidoc

@@ -1,6 +1,8 @@
 [[dense-vector]]
 === Dense vector datatype
 
+experimental[]
+
 A `dense_vector` field stores dense vectors of float values.
 The maximum number of dimensions that can be in a vector should
 not exceed 500. The number of dimensions can be

docs/reference/mapping/types/sparse-vector.asciidoc

@@ -1,6 +1,8 @@
 [[sparse-vector]]
 === Sparse vector datatype
 
+experimental[]
+
 A `sparse_vector` field stores sparse vectors of float values.
 The maximum number of dimensions that can be in a vector should
 not exceed 500. The number of dimensions can be