fix api docs link

Author: joao-r-reis

doc/features/vectors/README.md

@@ -8,7 +8,7 @@ The `vector` type is handled by the driver the same way as any other CQL type. Y
 
 ## The `CqlVector<T>` C# type
 
-The [API documentation](cqlvector-api) for this class contains useful information. Here's some examples:
+The [API documentation][cqlvector-api] for this class contains useful information. Here's some examples:
 
 ### Creating vectors
 
@@ -153,4 +153,4 @@ var entity = vectorSearchData.SingleOrDefault();
 ```
 
 
-[cqlvector-api]: https://docs.datastax.com/en/drivers/csharp/latest/api/Cassandra.CqlVector-1.html
+[cqlvector-api]: https://docs.datastax.com/en/drivers/csharp/latest/api/Cassandra.CqlVector-1.html