Fix typo in vectors doc (facebookincubator#11137)

Summary:
Pull Request resolved: facebookincubator#11137

Fix typo in vectors doc

Reviewed By: pedroerp

Differential Revision: D63677270

fbshipit-source-id: 90d20218d46bd6c724c36ec88822d1ae5f541150

velox/docs/develop/vectors.rst

@@ -360,8 +360,8 @@ vector in a dictionary.
 innermost vector of a dictionary, e.g. Dict(Dict(Flat))->wrappedVector() return
 Flat.
 
-**wrappedIndex(index)** virtual method defined in BaseVector translates index into
-the dictionary vector into an index into the innermost vector, e.g.
+**wrappedIndex(index)** virtual method defined in BaseVector translates the index in
+the dictionary vector into the index in the innermost vector, e.g.
 wrappedIndex(3) returns 6 for the dictionary vector above.
 
 Dictionary vector has its own nulls buffer independent of the nulls buffer of
@@ -530,7 +530,7 @@ to a particular row in another vector.
     vector_size_t index_;
 
 The following diagram shows a complex vector of type ARRAY(INTEGER) representing
-an array of 3 integers: [10, 12, -1, 0]. It is defined as a pointer to row 2 in
+an array of 4 integers: [10, 12, -1, 0]. It is defined as a pointer to row 2 in
 some other ArrayVector.
 
 .. image:: images/constant-array-vector.png
@@ -553,7 +553,7 @@ referring to the innermost vector, e.g. wrapInConstant(100, 5, Dict
 **wrappedVector()** virtual method defined in BaseVector provides access to the
 underlying flat vector.
 
-**wrappedIndex(index)** virtual method defined in BaseVector returns the index into
+**wrappedIndex(index)** virtual method defined in BaseVector returns the index in
 the underlying flat vector that identifies the constant value. This method
 returns the same value for all inputs as all rows of the constant vector map to
 the same row of the underlying flat vector.