Update src/items/functions.md

Co-Authored-By: Mazdak Farrokhzad <[email protected]>

Author: nikomatsakis

src/items/functions.md

@@ -288,7 +288,7 @@ call itself -- in the snippet above, for example, the `unsafe_example`
 function took a pointer `x` as argument, and then (when awaited)
 dereferenced that pointer. This implies that `x` would have to be
 valid until the future is finished executing, and it is the callers
-job to ensure that.
+responsibility to ensure that.
 
 ## Attributes on functions