Fix typo

Author: onagurna

README.md

@@ -100,7 +100,7 @@ https://url-to-pdf-api.herokuapp.com/api/render?url=http://google.com&waitFor=10
 
 https://url-to-pdf-api.herokuapp.com/api/render?url=http://google.com&attachmentName=google.pdf
 
-**Wait for an element macthing the selector `input` appears.**
+**Wait for an element matching the selector `input` appears.**
 
 https://url-to-pdf-api.herokuapp.com/api/render?url=http://google.com&waitFor=input