Fix assert_unsafe_precondition doc typos

Author: saethlin

library/core/src/intrinsics.rs

@@ -2597,7 +2597,7 @@ pub(crate) const fn debug_assertions() -> bool {
 /// These checks are behind a condition which is evaluated at codegen time, not expansion time like
 /// [`debug_assert`]. This means that a standard library built with optimizations and debug
 /// assertions disabled will have these checks optimized out of its monomorphizations, but if a
-/// a caller of the standard library has debug assertions enabled and monomorphizes an expansion of
+/// caller of the standard library has debug assertions enabled and monomorphizes an expansion of
 /// this macro, that monomorphization will contain the check.
 ///
 /// Since these checks cannot be optimized out in MIR, some care must be taken in both call and
@@ -2606,8 +2606,8 @@ pub(crate) const fn debug_assertions() -> bool {
 /// combination of properties ensures that the code for the checks is only compiled once, and has a
 /// minimal impact on the caller's code size.
 ///
-/// Caller should also introducing any other `let` bindings or any code outside this macro in order
-/// to call it. Since the precompiled standard library is built with full debuginfo and these
+/// Callers should also avoid introducing any other `let` bindings or any code outside this macro in
+/// order to call it. Since the precompiled standard library is built with full debuginfo and these
 /// variables cannot be optimized out in MIR, an innocent-looking `let` can produce enough
 /// debuginfo to have a measurable compile-time impact on debug builds.
 ///