More package lines.

core/simd/simd.odin

@@ -1,5 +1,5 @@
 /*
-The SIMD support package.
+package simd implements cross-platform SIMD support types and procedures.
 
 SIMD (Single Instruction Multiple Data), is a CPU hardware feature that
 introduce special registers and instructions which operate on multiple units

core/simd/x86/doc.odin

@@ -0,0 +1,2 @@
+// package x86 implements SIMD intrinsics specific to the Intel x86 and AMD64 architectures.
+package simd_x86