doc: Simplify safety section ref doc of own_back<T>()

Author: jhg

src/lib.rs

@@ -66,9 +66,7 @@ pub unsafe fn free<T>(pointer: *mut T) {
 ///
 /// # Safety
 ///
-/// The pointer must be a valid reference and never call it twice or behavior is undefined.
-///
-/// That could produce a HEAP error that produce a crash.
+/// Invalid pointer or call it twice could cause an undefined behavior or heap error and a crash.
 #[doc(alias = "free")]
 #[cfg(any(feature = "alloc", feature = "std"))]
 #[inline]