html: fix package doc typo

Change-Id: Ic16f297e936cf10bafe0656f5db68cd422c430aa
Reviewed-on: https://go-review.googlesource.com/c/net/+/474217
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Roland Shoemaker <roland@golang.org>
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

html/doc.go

@@ -106,7 +106,7 @@ and as such does not resolve issues that may exist in the processed HTML,
 producing a literal interpretation of the input.
 
 If your use case requires semantically well-formed HTML, as defined by the
-WHATWG specifiction, the parser should be used rather than the tokenizer.
+WHATWG specification, the parser should be used rather than the tokenizer.
 */
 package html // import "golang.org/x/net/html"