Ignore .envrc for direnv users

`direnv` + `layout poetry` as described in [1] works well for me. I
haven't committed the `.envrc` file yet because I don't want to
introduce clutter for people who aren't using direnv, and because I
suppose in principle someone could choose to use a `layout python`
for a bog-standard virtualenv.

[1]: https://github.com/direnv/direnv/wiki/Python#poetry

.gitignore

@@ -30,6 +30,9 @@ __pycache__/
 /media_store/
 /uploads
 
+# For direnv uses
+/.envrc
+
 # IDEs
 /.idea/
 /.ropeproject/