Doxygenize the documentation comments

src/IceRegistersX8664.h

Index: src/IceRegistersX8664.h
diff --git a/src/IceRegistersX8664.h b/src/IceRegistersX8664.h
index 96567b270ed6a05047f12ae17579a39aa6f4de1a..a09a326f0a82207943250f4d4716a5b0dea8e3cb 100644
--- a/src/IceRegistersX8664.h
+++ b/src/IceRegistersX8664.h
@@ -22,8 +22,8 @@ namespace Ice {
 
 namespace RegX8664 {
 
-// An enum of every register. The enum value may not match the encoding
-// used to binary encode register operands in instructions.
+/// An enum of every register. The enum value may not match the encoding
+/// used to binary encode register operands in instructions.
 enum AllRegisters {
 #define X(val, encode, name64, name, name16, name8, scratch, preserved,        \
           stackptr, frameptr, isInt, isFP)                                     \
@@ -36,8 +36,8 @@ enum AllRegisters {
 #undef X
 };
 
-// An enum of GPR Registers. The enum value does match the encoding used
-// to binary encode register operands in instructions.
+/// An enum of GPR Registers. The enum value does match the encoding used
+/// to binary encode register operands in instructions.
 enum GPRRegister {
 #define X(val, encode, name64, name, name16, name8, scratch, preserved,        \
           stackptr, frameptr, isInt, isFP)                                     \
@@ -47,8 +47,8 @@ enum GPRRegister {
       Encoded_Not_GPR = -1
 };
 
-// An enum of XMM Registers. The enum value does match the encoding used
-// to binary encode register operands in instructions.
+/// An enum of XMM Registers. The enum value does match the encoding used
+/// to binary encode register operands in instructions.
 enum XmmRegister {
 #define X(val, encode, name64, name, name16, name8, scratch, preserved,        \
           stackptr, frameptr, isInt, isFP)                                     \
@@ -58,8 +58,8 @@ enum XmmRegister {
       Encoded_Not_Xmm = -1
 };
 
-// An enum of Byte Registers. The enum value does match the encoding used
-// to binary encode register operands in instructions.
+/// An enum of Byte Registers. The enum value does match the encoding used
+/// to binary encode register operands in instructions.
 enum ByteRegister {
 #define X(val, encode) Encoded_##val encode,
   REGX8664_BYTEREG_TABLE