Merge pull request #339 from jameshfisher/patch-1

correct grammatical mistake in intro paragraph

README.md

@@ -3,7 +3,7 @@
 Irmin is a library for persistent stores with built-in snapshot,
 branching and reverting mechanisms. It is designed to use a large
 variety of backends. Irmin is written in pure OCaml and does not
-depend on external C stubs; it aims is to run everywhere, from Linux
+depend on external C stubs; it aims to run everywhere, from Linux
 to Xen unikernels.
 
 [![Build Status](https://travis-ci.org/mirage/irmin.svg)](https://travis-ci.org/mirage/irmin)