_content/doc: add link to /gopls

The linked content will go live with the release of gopls/v0.20.

Updates golang/go#68977

Change-Id: Ib266dea60f953f6f6ada6f10e86ed39603b43cd3
Reviewed-on: https://go-review.googlesource.com/c/website/+/690975
Reviewed-by: Robert Findley <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: adonovan

_content/doc/index.html

@@ -381,8 +381,10 @@ <h3>Tools</h3>
 <li><a href="/doc/articles/race_detector.html" aria-describedby="index-description">Data Race Detector</a> - a manual for the data race detector.</li>
 <li><a href="/doc/asm" aria-describedby="index-description">A Quick Guide to Go's Assembler</a> - an introduction to the assembler used by Go.</li>
 <li><a href="/blog/c-go-cgo" aria-describedby="index-description">C? Go? Cgo!</a> - linking against C code with <a href="/cmd/cgo/" aria-describedby="index-description">cgo</a>.</li>
-<li><a href="/blog/profiling-go-programs" aria-describedby="index-description">Profiling Go Programs</a></li>
+<li><a href="/blog/profiling-go-programs" aria-describedby="index-description">Profiling Go Programs</a> - tools for measuring your code's CPU and memory usage</li>
 <li><a href="/blog/race-detector" aria-describedby="index-description">Introducing the Go Race Detector</a> - an introduction to the race detector.</li>
+<li><a href="/gopls" aria-describedby="index-description">Gopls: The language server for Go
+</a> - getting the most out your editor when working in Go.</li>
 </ul>
 
 </section>