Documentation bug

Hello Sir/Ma'am,This is Gaurav Singh, one of the many users of the Bison tool. Thanks a lot for creating such a good tool, for it has opened a lot of new doors to me.I've written this email in order to inform you about a bug located in the documentation of this project( or more precisely an incorrect term ). In this section, you have used the heading 'Explanation of expr' in order to explain about a grouping named expr, whereas the grammar that you have refer to (i.e. this one) does not contain any such grouping. But based on the term referred to in the content that lies within the above mentioned section, instead of expr it should have been exp in the heading. Although it's a minute mistake but still it may throw off a beginner like me off the tracks for a moment. Hence, if you could take
  care of it, then the documentation would become much more better for the future readers. With this, I would like to thank you again for creating such an awesome tool.
Hope to see the issue rectified soon.With regards,Gaurav Singh