Merge pull request BoostIO#188 from less-easy-way/patch-1

Just fix a trivial typo.

Author: sota1235

docs/build.md

@@ -46,7 +46,7 @@ By this, webpack will watch the code changes and apply it automatically.
 We use Grunt.
 Acutal deploy can be run by `grunt`. However, you shouldn't use because the default task is including codesign and authenticode.
 
-So, we prepare a script which just make an excutable file.
+So, we prepare a script which just make an executable file.
 
 ```
 grunt pre-build