fix typo

close #143

Author: randy3k

README.md

@@ -114,7 +114,7 @@ SendCode expands following variables in the `cmd` field:
 - `$file`, the full path to the file
 - `$file_path`, the directory contains the file
 - `$file_name`, the file name
-- `$file_basename`, the file name without extension
+- `$file_base_name`, the file name without extension
 - `$file_extension`, the file extension
 - `$folder`, the first folder of current window
 - `$project_path`, the directory where sublime-project is stored