compress/flate: fix the old url for the flate algorithm

Change-Id: I84b74bc96516033bbf4a01f9aa81fe60d5a41355
Reviewed-on: https://go-review.googlesource.com/c/155317Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/compress/flate/inflate.go

@@ -89,7 +89,7 @@ type Resetter interface {
 // number of bits.
 //
 // See the following:
-//	http://www.gzip.org/algorithm.txt
+//	https://github.com/madler/zlib/raw/master/doc/algorithm.txt
 
 // chunk & 15 is number of bits
 // chunk >> 4 is value, including table link