doc: update frontend doc

Updates frontend doc to add new development
and build processes for scripts.

Change-Id: I518237682b2eb7a832a43d559c616b2aaf80bc3f
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/300553
Trust: Jamal Carvalho <jamal@golang.org>
Reviewed-by: Julie Qiu <julie@golang.org>
diff --git a/doc/frontend.md b/doc/frontend.md
index aec152e..c1ccc22 100644
--- a/doc/frontend.md
+++ b/doc/frontend.md
@@ -18,7 +18,8 @@
 
     go run ./cmd/frontend [-dev] [-direct_proxy]
 
-- The `-dev` flag reloads templates on each page load.
+- The `-dev` flag reloads templates on each page load and rebuilds JavaScript
+  assets when TypeScript source files change.
 
 The frontend can use one of three datasources:
 
@@ -84,23 +85,15 @@
 
 ## Static Assets
 
-A migration to TypeScript for pkg.go.dev is underway. See
-[#43359](https://github.com/golang/go/issues/43359) for tracking info.
-
-JavaScript assets for pkg.go.dev are built from TypeScript files in the
-content/static/js directory. All new scripts and updates to existing
-scripts should be written with TypeScript.
+JavaScript assets for pkg.go.dev are compiled from TypeScript files in the
+content/static/js directory. The compiled assets are commited to the repo so the
+frontend or worker service can be run without any additional steps from a new
+clone of the project.
 
 ### Building
 
-If you're modifying any TypeScript code, you must run
-`./all.bash npm run build` for the changes to take effect. This script will
-require Docker to be installed.
-
-### Development
-
-To watch the source files for changes and have them rebuilt automatically
-you can run `./all.bash npm run develop`.
+When modifying any TypeScript code, you must run
+`go run ./devtools/cmd/static` before commiting your changes.
 
 ### Testing