[turbolizer] Update Readme regarding typescript migration

Basically, remove 'Turbolizer is currently migrating to TypeScript.'

Bug: v8:7327
Change-Id: I83df1b4cf568e17c2e9393865702e5bb722a8b95
Notry: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2199353Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Auto-Submit: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67794}

tools/turbolizer/README.md

@@ -74,7 +74,6 @@ well as '--cpu' to specify which CPU to sample.
 Turbolizer build process
 ------------------------
 
-Turbolizer is currently migrating to TypeScript. The typescript sources reside in
-tools/turbolizer/src, and the typescript compiler will put the JavaScript output
-into tools/turbolizer/build/. The index.html file is set up to load the JavaScript
-from that directory.
+The typescript sources reside in tools/turbolizer/src, and the typescript
+compiler will put the JavaScript output into tools/turbolizer/build/. The
+index.html file is set up to load the JavaScript from that directory.