doc/go1.15: fix TODO about -buildmode=pie

Updates #37419.

Change-Id: If77067eb348de47a4b101325de8a43502383b6d3
Reviewed-on: https://go-review.googlesource.com/c/go/+/241740
Reviewed-by: Cherry Zhang <[email protected]>

Author: aclements

doc/go1.15.html

@@ -336,8 +336,10 @@ <h2 id="linker">Linker</h2>
 </p>
 
 <p><!-- CL 207877 -->
-  TODO: <a href="https://golang.org/cl/207877">https://golang.org/cl/207877</a>: Revert -buildmode=pie to internal linking.
-  The linker defaults to internal linking mode for PIE on linux/amd64 and linux/arm64, which does require a C linker.
+  The linker now defaults to internal linking mode
+  for <code>-buildmode=pie</code> on
+  <code>linux/amd64</code> and <code>linux/arm64</code>, so these
+  configurations no longer require a C linker.
 </p>
 
 <h2 id="objdump">Objdump</h2>