[DOC] tooling: improve doc

doc/tooling.md

@@ -1,40 +1,55 @@
 # 🦉 Tooling 🦉
 
+## Content
 
-To help work/improve/learn with OWL, we have here:
+- [Overview](#overview)
+- [Development Mode](#development-mode)
+- [Playground](#playground)
+- [Benchmarks](#benchmarks)
 
-- a benchmarks application
-- a playground application
+## Overview
 
-Both of them can be accessed by using a static http server.  A simple python
-server is available in `server.py`.  There is also a npm script to start it:
-`npm run extras` (and its version with a watcher: `npm run extras:watch`).
+To help work with/improve/learn OWL, there are a few extras tools/settings.
 
+- development mode: enable better error reporting for the developer
+- a playground application: a space to experiment and learn Owl.
+- a benchmarks application: allow comparison with a few common frameworks
 
-## Development mode
+The two applications are available in the `tools/` folder, and can be accessed
+by using a static http server. A simple python
+server is available in `server.py`. There is also a npm script to start it:
+`npm run tools` (and its version with a watcher: `npm run tools:watch`).
 
-By default, Owl is in *production* mode, this means that it will try to do its
-job fast, and skip some expensive operations.  However, in some cases, it is
+## Development Mode
+
+By default, Owl is in _production_ mode, this means that it will try to do its
+job fast, and skip some expensive operations. However, in some cases, it is
 convenient to have better information on what is going on, this is the purpose
 of the dev mode.
 
-Owl has a mode flag, in `owl.__info__.mode`.  Its default value is `prod`, but
+Owl has a mode flag, in `owl.__info__.mode`. Its default value is `prod`, but
 it can be set to `dev`:
 
 ```js
-owl.__info__.mode = 'dev';
+owl.__info__.mode = "dev";
 ```
 
 Note that templates compiled with the `prod` settings will not be recompiled.
 So, changing this setting is best done at startup.
 
-## Benchmarks
-
-The benchmarks application is a very small application, implemented in different
-frameworks, and in different versions of Owl.  This is a simple internal tool,
-useful to compare various performance metrics on some tasks.
-
 ## Playground
 
 The playground is an important application designed to help learning and
-experimenting with Owl.  It is available [online](https://odoo.github.io/owl/playground/).
+experimenting with Owl. The last published version of Owl can be tested [online](https://odoo.github.io/owl/playground/).
+
+It is an application similar to `jsFiddle`, but specialized for Owl: there are
+three tabs (`js`, `css` and `xml`), and a simple button `Run` to execute that
+code in an iframe.
+
+## Benchmarks
+
+Note: This is more an internal tool, useful for people working on Owl.
+
+The benchmarks application is a very small application, implemented in different
+frameworks, and in different versions of Owl. This is a simple internal tool,
+useful to compare various performance metrics on some tasks.