Added async/await example, added example with URL

Author: drdmitry

README.md

@@ -20,29 +20,93 @@ npm install --save conversiontools
 
 To use REST API - get API Token from the Profile page at https://conversiontools.io/profile.
 
+### Using Promises
+
 ```javascript
 const ConversionClient = require('conversiontools');
 
 // API Token from your Profile page at https://conversiontools.io/profile
 const apiToken = 'put the api token here';
 
-const conversion = new ConversionClient(apiToken);
+const conversionClient = new ConversionClient(apiToken);
+const conversionOptions = {
+  filename: 'test.xml',
+  timeout: 4000,
+  outputFilename: 'test.xml.csv',
+  options: {
+    delimiter: 'tab',
+  },
+};
+
+conversionClient
+  .run('convert.xml_to_csv', conversionOptions)
+  .then((filename) => {
+    console.log('File downloaded to', filename);
+  })
+  .catch(err => {
+    console.error('Conversion error', err);
+  });
+```
+
+### Using async/await
+
+```javascript
+const ConversionClient = require('conversiontools');
+
+// API Token from your Profile page at https://conversiontools.io/profile
+const apiToken = 'put the api token here';
 
-conversion
-  .run('convert.xml_to_csv', {
+const convert = async () => {
+  const conversionClient = new ConversionClient(apiToken);
+  const conversionOptions = {
     filename: 'test.xml',
     timeout: 4000,
     outputFilename: 'test.xml.csv',
     options: {
       delimiter: 'tab',
     },
-  })
-  .then((filename) => {
+  };
+  try {
+    const filename = await conversionClient.run('convert.xml_to_csv', conversionOptions);
     console.log('File downloaded to', filename);
-  })
-  .catch(err => {
-    console.log('Conversion error', err);
-  });
+  } catch (err) {
+    console.error('Conversion error', err);
+  }
+};
+
+convert();
+```
+
+### Conversion with URL
+
+The following example saving website page provided by the URL to JPG image.
+
+```javascript
+const ConversionClient = require('conversiontools');
+
+// API Token from your Profile page at https://conversiontools.io/profile
+const apiToken = 'put the api token here';
+
+const convert = async () => {
+  const conversionClient = new ConversionClient(apiToken);
+  const conversionOptions = {
+    url: 'https://en.wikipedia.org/wiki/Main_Page',
+    timeout: 4000,
+    outputFilename: 'wiki.jpg',
+    options: {
+      images: 'yes',
+      javascript: 'yes',
+    },
+  };
+  try {
+    const filename = await conversionClient.run('convert.website_to_jpg', conversionOptions);
+    console.log('File downloaded to', filename);
+  } catch (err) {
+    console.error('Conversion error', err);
+  }
+};
+
+convert();
 ```
 
 ## Documentation
@@ -53,4 +117,4 @@ List of available Conversion Types and corresponding conversion options can be f
 
 Licensed under [MIT](./LICENSE).
 
-Copyright (c) 2020 [Conversion Tools](https://conversiontools.io)
+Copyright (c) 2020-2021 [Conversion Tools](https://conversiontools.io)