Improve tagline in README (#1881)

README.md

 # deno
 
+A secure JavaScript/TypeScript runtime built with V8, Rust, and Tokio
+
 |      **Linux & Mac**       |        **Windows**         |
 | :------------------------: | :------------------------: |
 | [![][tci badge]][tci link] | [![][avy badge]][avy link] |
@@ -10,8 +12,6 @@
 [tci badge]: https://travis-ci.com/denoland/deno.svg?branch=master
 [tci link]: https://travis-ci.com/denoland/deno
 
-Deno is a browser-like command line program for executing JavaScript.
-
 Deno aims to provide a productive and secure scripting environment for the
 modern programmer. It is built on top of V8, Rust, and TypeScript.
 

website/manual.md

@@ -10,6 +10,8 @@ notice. [Bug reports](https://github.com/denoland/deno/issues) do help!
 
 ## Introduction
 
+A secure JavaScript/TypeScript runtime built with V8, Rust, and Tokio
+
 ### Philosophy
 
 Deno aims to be a productive and secure scripting environment for the modern
@@ -62,6 +64,14 @@ Deno provides <a href="https://github.com/denoland/deno_std">a set of reviewed
 
 - [Aims to support top-level `await`.](https://github.com/denoland/deno/issues/471)
 
+- Be able to serve HTTP efficently.
+  ([Currently it is relatively slow.](https://deno.land/benchmarks.html#req-per-sec))
+
+- Provide useful tooling out of the box: Built-in command-line debugger
+  [not yet](https://github.com/denoland/deno/issues/1120), built-in lint
+  [not yet](https://github.com/denoland/deno/issues/1880), dependency inspector
+  (`deno --info`), built-in code formatter (`deno --fmt`),
+
 ### Non-goals
 
 - No `package.json`.