Name exception roles more consistently

S32-setting-library/Exception.pod

@@ -48,9 +48,9 @@ behavior: storing payload data, a backtrace, and providing stringification.
 It also provides an C<ID> method, which is used to identify exceptions
 for retrieving translated versions of error messages.
 
-=head2 X::OSError
+=head2 X::OS
 
-    role X::OSError { has $.os-error }
+    role X::OS { has $.os-error }
 
 for all errors that are triggered by some error reported by the operating
 system (failed IO, system calls, fork, memory allocation).
@@ -68,9 +68,9 @@ For IO related errors
 For errors that stem from incomplete implementations of the Perl 6 language.
 A full Perl 6.0 implementation should not throw such errors.
 
-=head2 X::Compilation
+=head2 X::Comp
 
-    role X::Syntax {
+    role X::Comp {
         has $.filename;
         has $.line;
         has $.column;