[mlir][memref] fix typo in documentation (NFC)

mlir/include/mlir/Dialect/MemRef/IR/MemRefOps.td

let description = [{
     An optional `alignment` attribute may be specified to ensure that the
     region of memory that will be indexed is aligned at the specified byte
     boundary.  This is consistent with the fact that memref.alloc supports such
     an optional alignment attribute. Note that in ISO C standard, neither alloc
     nor realloc supports alignment, though there is aligned_alloc but not
     aligned_realloc.
 
     ```mlir
-    %3 = memref.ralloc %src {alignment = 8} : memref<64xf32> to memref<124xf32>
+    %3 = memref.realloc %src {alignment = 8} : memref<64xf32> to memref<124xf32>
     ```
 
     Referencing the memref through the old SSA value after realloc is undefined
     behavior.
 
     ```mlir
     %new = memref.realloc %old : memref<64xf32> to memref<124xf32>
     %4 = memref.load %new[%index]   // ok
let description = [{
     operations) to precisely analyze references at compile-time using polyhedral
     techniques. This is possible because of the
     [restrictions on dimensions and symbols](Affine.md/#restrictions-on-dimensions-and-symbols)
     in these contexts.
   }];
 
   let arguments = (ins Arg<AnyMemRef, "the reference to load from",
                            [MemRead]>:$memref,
-                       Variadic<Index>:$indices,                       
+                       Variadic<Index>:$indices,
                        DefaultValuedOptionalAttr<BoolAttr, "false">:$nontemporal);
   let results = (outs AnyType:$result);
 
   let extraClassDeclaration = [{
     Value getMemRef() { return getOperand(0); }
     void setMemRef(Value value) { setOperand(0, value); }
     MemRefType getMemRefType() {
       return getMemRef().getType().cast<MemRefType>();
let description = [{
     techniques. This is possible because of the
     [restrictions on dimensions and symbols](Affine.md/#restrictions-on-dimensions-and-symbols)
     in these contexts.
   }];
 
   let arguments = (ins AnyType:$value,
                        Arg<AnyMemRef, "the reference to store to",
                            [MemWrite]>:$memref,
-                       Variadic<Index>:$indices,                       
+                       Variadic<Index>:$indices,
                        DefaultValuedOptionalAttr<BoolAttr, "false">:$nontemporal);
 
   let builders = [
     OpBuilder<(ins "Value":$valueToStore, "Value":$memref), [{
       $_state.addOperands(valueToStore);
       $_state.addOperands(memref);
     }]>];