Replace a note by normative waiver on optional feature

Take into account Greg Lueck comment
#388 (comment)

Also reformat some text to pass the CI.

adoc/chapters/device_compiler.adoc

@@ -205,9 +205,9 @@ Amongst other things, this restriction makes it illegal for a
     implementation defines the [code]#SYCL_EXTERNAL# macro as described in
     <<subsec:syclexternal>>.
 
-In the case of a manifestly constant-evaluated expression or
-conversion, any code accepted by the C++ standard in this case is also
-accepted in a SYCL <<device-function>>.
+In the case of a manifestly constant-evaluated expression or conversion, any
+code accepted by the C++ standard in this case is also accepted in a SYCL
+<<device-function>>.
 
 [NOTE]
 ====
@@ -386,6 +386,14 @@ in <<sec:backends>> must be defined by all conformant implementations.
 
 A number of kernel features defined by this SYCL specification are optional;
 they may be supported on some devices but not on other devices.
+
+As stated in <<sec:language.restrictions.kernels>>, the restrictions for
+optional kernel features do not apply to manifestly constant-evaluated
+expressions or conversions in device code.
+Device code may use optional features in manifestly constant-evaluated
+expressions or conversions even if the device does not support the optional
+feature.
+
 As described in <<sec:device-aspects>>, an application can test whether a device
 supports these features by testing whether the device has an associated aspect.
 The following aspects are those that correspond to optional kernel features:
@@ -446,16 +454,6 @@ the entire device image when [code]#KernelA# is submitted to device
 [code]#dev1#.
 ====
 
-[NOTE]
-====
-As stated in <<sec:language.restrictions.kernels>>, the restrictions
-for optional kernel features do not apply to manifestly
-constant-evaluated expressions or conversions in device code. Device
-code may use optional features in manifestly constant-evaluated
-expressions or conversions even if the device does not support the
-optional feature.
-====
-
 
 [[sec:device.attributes]]
 == Attributes for device code