doc/go1.17: remove TODO for ports section

I'm not aware of anything more to mention for ports.

Change-Id: I686df8a230a55ad7f4c5eae43ca27f85fad9dd84
Reviewed-on: https://go-review.googlesource.com/c/go/+/326409
Trust: Cherry Mui <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

doc/go1.17.html

@@ -120,10 +120,6 @@ <h3 id="arm64">ARM64</h3>
  stack frame pointers only on Linux, macOS, and iOS.
 </p>
 
-<p>
- TODO: complete the Ports section
-</p>
-
 <h2 id="tools">Tools</h2>
 
 <h3 id="go-command">Go command</h3>