fix url for type-piracy (#88)

Author: hyrodium

README.md

@@ -11,7 +11,7 @@ are defined as being members of the interval.
 
 This package is intended to implement a "minimal" foundation for
 intervals upon which other packages might build. In particular, we
-*encourage* [type-piracy](https://docs.julialang.org/en/stable/manual/style-guide/#Avoid-type-piracy-1)
+*encourage* [type-piracy](https://docs.julialang.org/en/v1/manual/style-guide/#Avoid-type-piracy)
 for the reason that only one interval package can
 unambiguously define the `..` and `±` operators (see below).