Fix typos “an”→“a”

library/stdarch/crates/core_arch/src/x86/sse.rs

@@ -1000,7 +1000,7 @@ pub const fn _MM_SHUFFLE(z: u32, y: u32, x: u32, w: u32) -> i32 {
 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_shuffle_ps)
 ///
 /// Note that there appears to be a mistake within Intel's Intrinsics Guide.
-/// `_mm_shuffle_ps` is supposed to take an `i32` instead of an `u32`
+/// `_mm_shuffle_ps` is supposed to take an `i32` instead of a `u32`
 /// as is the case for [other shuffle intrinsics](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_shuffle_).
 /// Performing an implicit type conversion between an unsigned integer and a signed integer
 /// does not cause a problem in C, however Rust's commitment to strong typing does not allow this.

library/stdarch/crates/std_detect/src/detect/arch/x86.rs

@@ -2,7 +2,7 @@
 //!
 //! The features are detected using the `detect_features` function below.
 //! This function uses the CPUID instruction to read the feature flags from the
-//! CPU and encodes them in an `usize` where each bit position represents
+//! CPU and encodes them in a `usize` where each bit position represents
 //! whether a feature is available (bit is set) or unavaiable (bit is cleared).
 //!
 //! The enum `Feature` is used to map bit positions to feature names, and the