Added reference to Haskell PVP for versioning.

Author: lukehoersten

README.md

@@ -10,7 +10,9 @@ This is the Haskell implementation of [multihash](https://github.com/multiformat
 
 ## Install
 
-`stack install`
+This package can be installed with [stack](https://haskellstack.org/), a common Haskell package manager.
+
+`$ stack install`
 
 ## Usage
 
@@ -22,6 +24,8 @@ TODO
 
 ## Contribute
 
+This package follows the Haskell [Haskell Package Versioning Policy](https://pvp.haskell.org).
+
 Contributions welcome: please [open an issue](https://github.com/multiformats/haskell-multihash/issues).
 
 Check out our [contributing document](https://github.com/multiformats/multiformats/blob/master/contributing.md) for more information on how we work, and about contributing in general. Please be aware that all interactions related to multiformats are subject to the IPFS [Code of Conduct](https://github.com/ipfs/community/blob/master/code-of-conduct.md).