updating README.md with details, examples and credits

Author: carloscarucce

README.md

@@ -2,7 +2,11 @@
 
 [![codecov](https://codecov.io/gh/WebdevCave/jwt/graph/badge.svg?token=U0OXfWrDJl)](https://codecov.io/gh/WebdevCave/jwt)
 
-![JWT Logo](https://jwt.io/img/logo-asset.svg)
+<div style="text-align: center">
+<a href="https://jwt.io/" target="_blank">
+<img src="https://jwt.io/img/logo-asset.svg">
+</a>
+</div>
 
 ## How to install
 
@@ -29,38 +33,83 @@ composer require webdevcave/jwt
         <td>HS512</td>
         <td>1.0</td>
     </tr>
+    <tr>
+        <td>RS256</td>
+        <td>1.1</td>
+    </tr>
+    <tr>
+        <td>RS384</td>
+        <td>1.1</td>
+    </tr>
+    <tr>
+        <td>RS512</td>
+        <td>1.1</td>
+    </tr>
 </table>
 
 ## Provided claim validators
 <table>
     <tr>
         <th>Claim</th>
         <th>Version</th>
+        <th>Description</th>
+        <th>RFC</th>
+    </tr>
+    <tr>
+        <td>aud</td>
+        <td>1.1</td>
+        <td>Audience</td>
+        <td>https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.3</td>
     </tr>
     <tr>
         <td>exp</td>
         <td>1.0</td>
+        <td>Expiration time (timestamp)</td>
+        <td>https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.4</td>
+    </tr>
+    <tr>
+        <td>iss</td>
+        <td>1.1</td>
+        <td>Issuer</td>
+        <td>https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.1</td>
     </tr>
     <tr>
         <td>nbf</td>
         <td>1.0</td>
+        <td>Not before (timestamp)</td>
+        <td>https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.5</td>
+    </tr>
+    <tr>
+        <td>sub</td>
+        <td>1.1</td>
+        <td>Subject</td>
+        <td>https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.2</td>
     </tr>
 </table>
 
+
+- "typ" claim is defined as JWT by default.
+- "iat" and "nbf" claims are starts with the current timestamp by default.
+- "jti" validator isn't provided but it can be implemented by your application as presented in "Validating your private 
+claims" section
+
 ## Basic Usage
 
-### Generating token
+### Generating a token
+
 ```php
 <?php
 
 use Webdevcave\Jwt\Token;
 use Webdevcave\Jwt\SignerFactory;
+use \Webdevcave\Jwt\Secrets\HsSecret;
 
+$secret = new HsSecret('your_secret_here');
 $token = Token::create()
-            ->with('exp', strtotime('+ 1 hour')) //Expires in one hour
-            ->withSigner(SignerFactory::build('HS256')) //HS256 signer is provided by default. This could be omitted
-            ->sign($mySecret)
-            ->toString();
+    ->withSigner(SignerFactory::build('HS256')) //HS256 signer is provided by default. This could be omitted
+    ->with('exp', strtotime('+ 1 hour')) //Expires in one hour
+    ->sign($secret)
+    ->toString();
 ```
 
 ### Validating and reading values from a token
@@ -70,15 +119,49 @@ $token = Token::create()
 use Webdevcave\Jwt\Token;
 
 $token = Token::fromString('xxxx.yyyyy.zzzzz');
-
-$isValid = $token->validate($mySecret);
+$isValid = $token->validate($secret);
 
 if ($isValid) {
     $payload = $token->getPayload();
     $headers = $token->getHeaders();
 }
 ```
 
+### RSA Tokens:
+
+First of all, you will need a public/private key pair. If you don't have one, you can generate it easily at the 
+following page: https://cryptotools.net/rsagen
+
+With your public/private key pair in hand, the process will be similar to the hmac tokens in the above example:
+
+```php
+<?php
+
+use Webdevcave\Jwt\Token;
+use Webdevcave\Jwt\SignerFactory;
+use \Webdevcave\Jwt\Secrets\RsSecret;
+
+$secret = new RsSecret('private_key', 'public_key');
+
+//Generate a token string
+$tokenString = Token::create()
+    ->withSigner(SignerFactory::build('RS256'))
+    ->with('exp', strtotime('+ 1 hour')) //Expires in one hour
+    ->sign($secret)
+    ->toString();
+
+//Validating...
+$token = Token::fromString($tokenString);
+if ($token->validate($secret)) {
+    //token is valid...
+    $creationDate = date(DATE_RFC3339, $token->getPayload('iat'));
+    $expirationDate = date(DATE_RFC3339, $token->getPayload('exp'));
+    
+    echo "Your token was created at $creationDate.";
+    echo "It will expire at $expirationDate.";
+}
+```
+
 ### Validating your private claims
 
 First you have to create your validator
@@ -124,3 +207,33 @@ if ($isValid) {
     $myClaim = $token->getPayload('my-claim');
 }
 ```
+
+## Shortcuts
+
+You can get an Token instance directly from the Authorization header or through a query parameter with the following 
+methods:
+
+```php
+
+use Webdevcave\Jwt\Token;
+
+//Load from authorization bearer
+$token1 = Token::fromAuthorizationBearer();
+
+//Load from get parameters
+$token2 = Token::fromQueryString('token');
+$token3 = Token::fromQueryString('token2');
+```
+
+## Contributing
+
+Contributions are welcome! If you find any issues or have suggestions for improvements,
+please open an issue or a pull request on GitHub.
+
+## License
+
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
+
+## Credits
+
+Original project can be found [here](https://github.com/corviz/jwt)