Fix make-->vector doc typo.

Closes PR 11698.

Merge to 5.1.

collects/mzlib/scribblings/struct.scrbl

@@ -60,7 +60,7 @@ property.
 ]}
 
 
-@defform[(make->vector struct-id)]{
+@defform[(make-->vector struct-id)]{
 
 Builds a function that accepts a structure type instance (matching
 @scheme[struct-id]) and provides a vector of the fields of the

collects/scribblings/guide/contracts-exists.scrbl

@@ -44,7 +44,7 @@ data structure (perhaps accidentally) and thus any change in the representation
 (say to a more efficient representation that supports amortized constant time
 enqueue and dequeue operations) might break client code.
 
-To ensure that the stack representation is abstact, we can use @racket[#:∃] in the
+To ensure that the stack representation is abstract, we can use @racket[#:∃] in the
 @racket[provide/contract] expression, like this:
 @racketblock[(provide/contract
               #:∃ stack

collects/scribblings/guide/contracts-structure.scrbl

@@ -224,7 +224,7 @@ racket
   
 (code:comment "bst-between : number number -> contract")
 (code:comment "builds a contract for binary search trees")
-(code:comment "whose values are betweeen low and high")
+(code:comment "whose values are between low and high")
 (define (bst-between/c low high)
   (or/c null?
         (node/dc [val (between/c low high)]

src/plot/plplot/plot3d.c

@@ -519,7 +519,7 @@ plsurf3d(PLFLT *x, PLFLT *y, PLFLT **z, PLINT nx, PLINT ny,
 		if (ct == 2) {
 
 		  /* yes, xx and yy are the intersection points of the triangle with
-		   * the contour line -- draw a straight line betweeen the points
+		   * the contour line -- draw a straight line between the points
 		   * -- at the end this will make up the contour line */
 
 		  if (opt & SURF_CONT) {