Keyword argument fix

Author: JonasJasas

README.md

@@ -37,7 +37,7 @@ Example to convert file to PDF. All supported formats and options can be found
 [here](https://www.convertapi.com/doc/supported-formats).
 
 ```ruby
-result = ConvertApi.convert('pdf', File: '/path/to/my_file.docx')
+result = ConvertApi.convert('pdf', { File: '/path/to/my_file.docx' })
 
 # save to file
 result.file.save('/path/to/save/file.pdf')
@@ -59,16 +59,16 @@ conversion_cost = result.conversion_cost
 #### Convert file url
 
 ```ruby
-result = ConvertApi.convert('pdf', File: 'https://website/my_file.docx')
+result = ConvertApi.convert('pdf', { File: 'https://website/my_file.docx' })
 ```
 
 #### Specifying from format
 
 ```ruby
 result = ConvertApi.convert(
   'pdf', 
-  { File: /path/to/my_file' }, 
-  from_format: 'docx'
+  { File: /path/to/my_file', 
+  from_format: 'docx' }
 )
 ```
 
@@ -80,9 +80,9 @@ parameters and explanations can be found [here](https://www.convertapi.com).
 ```ruby
 result = ConvertApi.convert(
   'pdf', 
-  File: /path/to/my_file.docx',
+  { File: /path/to/my_file.docx',
   PageRange: '1-10',
-  PdfResolution: '150',
+  PdfResolution: '150' }
 )
 ```
 
@@ -91,7 +91,7 @@ result = ConvertApi.convert(
 You can access result file collection like this:
 
 ```ruby
-result = ConvertApi.convert('pdf', File: 'https://website/my_file.docx')
+result = ConvertApi.convert('pdf', { File: 'https://website/my_file.docx' })
 
 puts result.files[0].url
 puts result.files[0].size