New bios api description was added

doc/api/api-bios.rst

@@ -0,0 +1,52 @@
+BIOS Contract
+=============
+
+Overview
+--------
+
+``Bios.sol`` - is the main kernel smartcontract with all the logic about consensus, staking and voting. Its based on the ``QueueHelper`` that brings queue implementation code.
+Latest version of the Bios contact you can always  `find in our repo <https://github.com/papyrusglobal/papyrus/blob/master/papyrus-stuff/contracts/Bios.sol>`_
+
+BIOS Addresses
+--------------
+
+Testnet BIOS address : `0x8f98d0aa9b01e7d15a7950db68b26b89d6f1be14 <http://explorer-testnet.papyrus.network/addr/0x8f98d0aa9b01e7d15a7950db68b26b89d6f1be14#tab_addr_1>`_ 
+Testnet `BIOS Abi <https://github.com/papyrusglobal/explorer/blob/master/abi/bios.json>`_  
+
+BIOS Usages examples
+--------------------
+
+Let's take a look at the simple example of Javascript code that will get all authorities nodes from our BIOS contract. 
+
+.. code-block:: javascript
+      :emphasize-lines: 2, 7, 14
+
+	const { eth } = require('./web3relay');
+	const ABI = require('../abi/bios');
+	const { getConfig } = require('../utils');
+
+	const config = getConfig();
+	if (!config.biosAddress) throw new Error('Setup config.biosAddres');
+	const contract = new eth.Contract(ABI, config.biosAddress);
+
+	module.exports = function (req, res) {
+	  if (typeof contract.methods.getAuthorities !== 'function') {
+	    console.error('Contract method \'getAuthorities\' not found', err);
+	    res.send([]);
+	    res.end();
+	  }
+	  contract.methods.getAuthorities().call()
+	    .then(authorities => {
+	      res.send(authorities);
+	      res.end();
+	    })
+	    .catch(err => {
+	      console.error('Can\'t get authorities from contract. Silently return empty array', err);
+	      res.send([]);
+	      res.end();
+	    })
+	};
+
+
+If you are interested to see more examples how to call BIOS contact API you could check our API documentation sections for example - `Voting API <https://papyrus-network.readthedocs.io/en/latest/doc/api/api-staking.html#api-usage-example>`_
+