Apostrophe type removed

Author: dimwight

docs/compiler/program.md

@@ -8,7 +8,7 @@ Its interaction mechanism with the OE:
 
 `Program` *-uses->* `CompilerHost` *-uses->* `System`
 
-The reason for having a `CompilerHost` as a point of indirection is that it allows it's interface to be more finely tuned for `Program` needs and not bother with OE needs (e.g. the `Program` doesn't care about `fileExists` a function provided by `System`).
+The reason for having a `CompilerHost` as a point of indirection is that it allows its interface to be more finely tuned for `Program` needs and not bother with OE needs (e.g. the `Program` doesn't care about `fileExists` a function provided by `System`).
 
 There are other users of `System` as well (e.g. tests).