gopls/doc: fix composites analyzer name

Not composite, but compositeS.

Change-Id: I5549653748bef90338263aea0380f662eba723d3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/237682
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
diff --git a/gopls/doc/analyzers.md b/gopls/doc/analyzers.md
index f3e5eee..e56a52f 100644
--- a/gopls/doc/analyzers.md
+++ b/gopls/doc/analyzers.md
@@ -71,7 +71,7 @@
 
 Default value: `true`.
 
-### **composite**
+### **composites**
 
 check for unkeyed composite literals