gopls/doc: tidy up analyzer documentation

Details:
- add introduction.
- change generator to put title in H2 heading,
  and add anchors.
- organize list of analyzers in gopls settings.
- fix typos.

Change-Id: Ie559a331a2ac51171c366104416d53a8329afe7c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/586779
Reviewed-by: Robert Findley <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Alan Donovan <[email protected]>

Author: adonovan

go/analysis/passes/copylock/copylock.go

@@ -31,7 +31,7 @@ values should be referred to through a pointer.`
 var Analyzer = &analysis.Analyzer{
 	Name:             "copylocks",
 	Doc:              Doc,
-	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/copylocks",
+	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/copylock",
 	Requires:         []*analysis.Analyzer{inspect.Analyzer},
 	RunDespiteErrors: true,
 	Run:              run,