Rename DOC.md to README.md in docs, and add intro in main README.md.

Author: viferga

README.md

@@ -1,16 +1,30 @@
 <div align="center">
   <a href="https://metacall.io" target="_blank"><img src="https://raw.githubusercontent.com/metacall/core/master/deploy/images/logo.png" alt="METACALL" style="max-width:100%; margin: 0 auto;" width="80" height="80">
   <h1><b>MetaCall Polyglot Runtime</b></h1></a>
+  <a href="https://metacall.io">MetaCall.io</a> |
   <a href="https://github.com/metacall/install">Install</a> |
-  <a href="https://github.com/metacall/core/blob/master/docs/DOC.md">Docs</a> |
+  <a href="https://github.com/metacall/core/blob/master/docs/README.md">Docs</a> |
   <a href="https://t.me/joinchat/BMSVbBatp0Vi4s5l4VgUgg">Telegram</a> |
   <a href="https://discord.gg/upwP4mwJWa">Discord</a> |
   <a href="https://matrix.to/#/!wOPPTChTestHdAHEOf:matrix.org">Matrix</a>
-</div>
-
-**MetaCall** is an extensible, embeddable and interoperable multi-language polyglot runtime distributed as a binary and library. It allows calling functions, methods or procedures between JavaScript, NodeJS, TypeScript, Python, Ruby, C#, Go, C, C++, Rust, D or Cobol.
 
-<div align="center">
   <a href="https://medium.com/@metacall/call-functions-methods-or-procedures-between-programming-languages-with-metacall-58cfece35d7" target="_blank"><img src="https://raw.githubusercontent.com/metacall/core/master/deploy/images/overview.png" alt="M E T A C A L L" style="max-width:100%; margin: 0 auto;" width="350" height="auto"></a>
 </div>
 
+**MetaCall** allows calling functions, methods or procedures between multiple programming languages.
+
+`sum.py`
+``` python
+def sum(a, b):
+  return a + b
+```
+
+`main.js`
+``` javascript
+const { sum } = require('sum.py');
+
+sum(3, 4); // 7
+```
+
+**MetaCall** is an extensible, embeddable and interoperable polyglot runtime. It supports NodeJS, Vanilla JavaScript, TypeScript, Python, Ruby, C#, Go, C, C++, Rust, D, Cobol [and more](https://github.com/metacall/core/blob/master/docs/README.md#2-language-support). Use the [installer](https://github.com/metacall/install) and try [some examples](https://github.com/metacall/beautifulsoup-express-example).
+