http/httpproxy: remove comment on https proxy precedance

For golang/go#40909
For golang/go#54890

Change-Id: I1de1803f8fd00f54290404a8760d9f704ff766c3
Reviewed-on: https://go-review.googlesource.com/c/net/+/428795
Auto-Submit: Damien Neil <dneil@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
diff --git a/http/httpproxy/proxy.go b/http/httpproxy/proxy.go
index 16994ac..c3bd9a1 100644
--- a/http/httpproxy/proxy.go
+++ b/http/httpproxy/proxy.go
@@ -81,8 +81,7 @@
 
 // FromEnvironment returns a Config instance populated from the
 // environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the
-// lowercase versions thereof). HTTPS_PROXY takes precedence over
-// HTTP_PROXY for https requests.
+// lowercase versions thereof).
 //
 // The environment values may be either a complete URL or a
 // "host[:port]", in which case the "http" scheme is assumed. An error