Add a rule about the indentation of multi-arity functions
Translate "multiple-arity-indentation" rule
Update the indentation of the threading macro examples
Clarify the indentation rules

by Bozhidar Batsov
Threading macros do not have bodies.

by Marshall Bockrath-Vandegrift
Fix indentation -> list-inclusion of code-block.

by Marshall Bockrath-Vandegrift
Tabs -> spaces.

by Marshall Bockrath-Vandegrift
Clarify state of `use`.

by Marshall Bockrath-Vandegrift
Set predicate `#{0}` -> `#{1}`

The set `#{0}` is a suboptimal example because the core predicate
`zero?` would be even more appropriate.

Conflicts:
	README.md