doc/go1.14: remove TODO about Illumos port

There is an active builder that was added in CL 201597,
and it is passing on Go tip and release-branch.go1.13
(with one failure that appears to be flaky due to being
out of memory). It's also passing on all golang.org/x repos
on tip and release-branch.go1.13. It's not configured to
run on Go 1.12 release branches.

Updates #36878
Updates #15581

Change-Id: I4ed7fc62c11a09743832fca39bd61fa0cf6e7ded
Reviewed-on: https://go-review.googlesource.com/c/go/+/217737
Reviewed-by: Ian Lance Taylor <[email protected]>
Reviewed-by: Alexander Rakoczy <[email protected]>

Author: dmitshur

doc/go1.14.html

@@ -52,11 +52,6 @@ <h2 id="language">Changes to the language</h2>
 
 <h2 id="ports">Ports</h2>
 
-<p>
-  TODO: is Illumos up with a builder and passing?
-  https://golang.org/issue/15581.
-</p>
-
 <p>
   TODO: announce something about the Go Solaris port? Solaris itself
   is unmaintained? The builder is still running at Oracle, but the