[Polly] Fix typo. NFC.

[grosser]

Thank you Nandini! I just committed this!

include/polly/ScopInfo.h

   ///     LLVM-IR are commonly expressed as a single-dimensional access with a
   ///     complicated access function, are modeled as multi-dimensional
   ///     memory objects (grep for "delinearization").
   Array,
 
   /// MemoryKind::Value: Models an llvm::Value
   ///
   /// Memory objects of type MemoryKind::Value are used to model the data flow
   /// induced by llvm::Values. For each llvm::Value that is used across
-  /// BasicBocks one ScopArrayInfo object is created. A single memory WRITE
+  /// BasicBlocks, one ScopArrayInfo object is created. A single memory WRITE
   /// stores the llvm::Value at its definition into the memory object and at
   /// each use of the llvm::Value (ignoring trivial intra-block uses) a
   /// corresponding READ is added. For instance, the use/def chain of a
   /// llvm::Value %V depicted below
   ///              ______________________
   ///              |DefBB:              |
   ///              |  %V = float op ... |
   ///              ----------------------
   ///               |                  |