Give a few roles a subtitle

Author: moritz

lib/Type/Callable.pod

@@ -2,6 +2,8 @@
 
 =TITLE role Callable
 
+=SUBTITLE Common role for invocable code
+
     role Callable { ... }
 
 Role for objects which support calling them. It's used in L<Block>,

lib/Type/IO.pod

@@ -2,6 +2,8 @@
 
 =TITLE role IO
 
+=SUBTITLE Tag role for all input/output types
+
     role IO { }
 
 The IO role provides no functionality itself, and moreso just marks if a

lib/Type/Numeric.pod

@@ -2,6 +2,8 @@
 
 =TITLE role Numeric
 
+=SUBTITLE Common role for numbers and types that can act as numbers
+
     role Numeric { ... }
 
 Common role for numbers and types that can act as numbers.

lib/Type/X/Comp.pod

@@ -2,6 +2,8 @@
 
 =TITLE role X::Comp
 
+=SUBTITLE Common role for compile-time errors
+
     role X::Comp is Exception { }
 
 Common role for compile-time errors.