Clarify unsafe to safe function qualifier change.

Author: ehuss

src/doc/src/reference/semver.md

@@ -88,7 +88,7 @@ considered incompatible.
         * [Possibly-breaking: introducing a new function type parameter](#fn-generic-new)
         * [Minor: generalizing a function to use generics (supporting original type)](#fn-generalize-compatible)
         * [Major: generalizing a function to use generics with type mismatch](#fn-generalize-mismatch)
-        * [Possibly-breaking: making an `unsafe` function safe](#fn-unsafe-safe)
+        * [Minor: making an `unsafe` function safe](#fn-unsafe-safe)
     * Attributes
         * [Major: switching from `no_std` support to requiring `std`](#attr-no-std-to-std)
         * [Major: adding `non_exhaustive` to an existing enum, variant, or struct with no private fields](#attr-adding-non-exhaustive)
@@ -1082,12 +1082,14 @@ fn main() {
 ```
 
 <a id="fn-unsafe-safe"></a>
-### Possibly-breaking: making an `unsafe` function safe
+### Minor: making an `unsafe` function safe
 
-A previously `unsafe` function can be made safe without breaking code. Note
-however that it will likely cause the [`unused_unsafe`][unused_unsafe] lint
-to trigger as in the example below, which will cause local crates that have
-specified `#![deny(warnings)]` to stop compiling.
+A previously `unsafe` function can be made safe without breaking code.
+
+Note however that it may cause the [`unused_unsafe`][unused_unsafe] lint to
+trigger as in the example below, which will cause local crates that have
+specified `#![deny(warnings)]` to stop compiling. Per [introducing new
+lints](#new-lints), it is allowed for updates to introduce new warnings.
 
 Going the other way (making a safe function `unsafe`) is a breaking change.
 
@@ -1118,33 +1120,7 @@ fn main() {
 
 Making a previously `unsafe` associated function or method on structs / enums
 safe is also a minor change, while the same is not true for associated
-function on traits:
-
-```rust,ignore
-// MAJOR CHANGE
-
-///////////////////////////////////////////////////////////
-// Before
-pub trait Foo {
-    unsafe fn foo();
-}
-
-///////////////////////////////////////////////////////////
-// After
-pub trait Foo {
-    fn foo();
-}
-
-///////////////////////////////////////////////////////////
-// Example usage that will break.
-use updated_crate::Foo;
-
-struct Bar;
-
-impl Foo for Bar {
-    unsafe fn foo() {} // Error: method `foo` has an incompatible type for trait
-}
-```
+function on traits (see [any change to trait item signatures](#trait-item-signature)).
 
 <a id="attr-no-std-to-std"></a>
 ### Major: switching from `no_std` support to requiring `std`