Update functions.md

Author: oli-obk

src/items/functions.md

@@ -185,9 +185,9 @@ Exhaustive list of permitted structures in const functions:
 * Reading from constants (but not statics, not even taking a reference to a static)
 * `&` and `*` (only dereferencing of references, not raw pointers)
 * Casts except for raw pointer to integer casts
-* `const unsafe fn` is allowed, but the body must consist of safe operations
-  only and you won't be able to call the `const unsafe fn` from within another
-  const function even if you use `unsafe`
+* `unsafe` blocks and `const unsafe fn` is allowed, but the body/block must consist
+  of safe operations or calls to other const functions only. Further unsafe operations
+  may get allowed in const functions in the future.
 
 ## Attributes on functions