Merge pull request #98 from tshepang/patch-2

Update 2016-05-13-rustup.md

Author: brson

_posts/2016-05-13-rustup.md

@@ -109,7 +109,7 @@ That's an easy way to verify your code works on the next Rust release. That's
 good Rust citizenship!
 
 We can use `rustup show` to show us the installed toolchains, and `rustup
-update` to keep the up to date with Rust's releases.
+update` to keep them up to date with Rust's releases.
 
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