Update features.md

* Updated macOS minimum SIMD support from SSSE3 to SSE4.1 as macOS Sierra and later require Penryn
* Included the minimum SIMD support for most Windows targets of SSE3

perf-guide/src/target-feature/features.md

@@ -6,7 +6,7 @@ and using a SIMD instruction which is not supported will trigger undefined behav
 To allow building safe, portable programs, the Rust compiler will **not**, by default,
 generate any sort of vector instructions, unless it can statically determine
 they are supported. For example, on AMD64, SSE2 support is architecturally guaranteed.
-The `x86_64-apple-darwin` target enables up to SSSE3. The get a defintive list of
+The `x86_64-apple-darwin` target enables up to SSE4.1 and 64-bit tier-1 Windows targets support SSE3. The get a defintive list of
 which features are enabled by default on various platforms, refer to the target
 specifications [in the compiler's source code][targets].