very minor spelling/grammar changes in README.md

Signed-off-by: Fedor Indutny <fedor@indutny.com>

README.md

@@ -75,7 +75,7 @@ if (parser->upgrade) {
 HTTP needs to know where the end of the stream is. For example, sometimes
 servers send responses without Content-Length and expect the client to
 consume input (for the body) until EOF. To tell http_parser about EOF, give
-`0` as the forth parameter to `http_parser_execute()`. Callbacks and errors
+`0` as the fourth parameter to `http_parser_execute()`. Callbacks and errors
 can still be encountered during an EOF, so one must still be prepared
 to receive them.
 
@@ -110,7 +110,7 @@ followed by non-HTTP data.
 information the Web Socket protocol.)
 
 To support this, the parser will treat this as a normal HTTP message without a
-body. Issuing both on_headers_complete and on_message_complete callbacks. However
+body, issuing both on_headers_complete and on_message_complete callbacks. However
 http_parser_execute() will stop parsing at the end of the headers and return.
 
 The user is expected to check if `parser->upgrade` has been set to 1 after
@@ -145,7 +145,7 @@ buffer to avoid copying memory around if this fits your application.
 
 Reading headers may be a tricky task if you read/parse headers partially.
 Basically, you need to remember whether last header callback was field or value
-and apply following logic:
+and apply the following logic:
 
     (on_header_field and on_header_value shortened to on_h_*)
      ------------------------ ------------ --------------------------------------------