A  typo in user guide doc 
There was a typo in user guide doc specifically in [Merge, join, concatenate and compare](https://pandas.pydata.org/docs/dev/user_guide/merging.html#) ,after fixing ,it is now making more sense while reading 
A major typo has been fixed now ,earlier it was not making any sense while reading that particular line of docs but now it is more intuitive and making more sense while reading Thanks @imTejasRajput 