doc: fix typo in go memory model doc

Fixes a typo where originally "may by" was written where the intent was
"may be".

Change-Id: Ia5ba51a966506395c41b17ca28d59f63bd487f3e
Reviewed-on: https://go-review.googlesource.com/c/go/+/693075
Reviewed-by: Dmitri Shuralyov <[email protected]>
Auto-Submit: Dmitri Shuralyov <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
TryBot-Bypass: Cherry Mui <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: derekparker

doc/go_mem.html

@@ -231,7 +231,7 @@ <h2 id="restrictions">Implementation Restrictions for Programs Containing Data R
 
 <p>
 A read of an array, struct, or complex number
-may by implemented as a read of each individual sub-value
+may be implemented as a read of each individual sub-value
 (array element, struct field, or real/imaginary component),
 in any order.
 Similarly, a write of an array, struct, or complex number