Replace `r` with `reddit`.
Replace `r` with `reddit`.

In PRAW<4 `r` was the typical variable name used for Reddit instances. This is
convenient, however, it encourages poor variable naming practices. In PRAW4+
documentation, this variable should always be named `reddit`.

13steinj/praw,praw-dev/praw,praw-dev/praw,nmtake/praw,gschizas/praw,leviroth/praw,gschizas/praw,13steinj/praw,darthkedrik/praw,leviroth/praw,nmtake/praw,darthkedrik/praw,RGood/praw,RGood/praw