Remove a stray backtick in the dense vector docs

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

@@ -123,7 +123,7 @@ positive and that a larger score corresponds to a higher ranking.
 `l2_norm`:::
 Computes similarity based on the L^2^ distance (also known as Euclidean
 distance) between the vectors. The document `_score` is computed as
-`1 / (1 + l2_norm(query, vector)^2)`.`
+`1 / (1 + l2_norm(query, vector)^2)`.
 
 `dot_product`:::
 Computes the dot product of two vectors. This option provides an optimized way