Update mg_http_parse_header.md

docs/c-api/http.h/mg_http_parse_header.md

@@ -7,17 +7,17 @@ signature: |
                            size_t buf_size);
 ---
 
-Parse HTTP header `hdr`. Find variable `var_name` and store it's value
+Parses the HTTP header `hdr`. Finds variable `var_name` and stores its value
-in the buffer `buf`, `buf_size`. Return 0 if variable not found, non-zero
+in the buffer `buf`, `buf_size`. Returns 0 if variable not found, non-zero
 otherwise.
 
 This function is supposed to parse
-cookies, authentication headers, etcetera. Example (error handling omitted):
+cookies, authentication headers, etc. Example (error handling omitted):
 
     char user[20];
     struct mg_str *hdr = mg_get_http_header(hm, "Authorization");
     mg_http_parse_header(hdr, "username", user, sizeof(user));
 
-Return length of the variable's value. If buffer is not large enough,
+Returns the length of the variable's value. If buffer is not large enough,
 or variable not found, 0 is returned.