add emphasis and a bit of extra usage info

doc/Language/modules.pod6

@@ -159,6 +159,21 @@ tags: C<ALL>, C<DEFAULT> and C<MANDATORY>.
     use MyModule :ALL;     #bag, pants, sunglasses, torch, underpants
     =end code
 
+Notes:
+
+1. The C<:MANDATORY> tag on an exported sub ensures it will be exported
+no matter whether the using program adds any tag or not.
+
+2. The space after the module name and before the tag is mandatory.
+
+3. Multiple tags may be used (separated by commas).  For example:
+
+    =begin code
+    # main.pl
+    use lib 'lib';
+    use MyModule :day, :night; #pants, sunglasses, torch
+    =end code
+
 =head3 UNIT::EXPORT::*
 
 Beneath the surface, C<is export> is adding the symbols to a C<UNIT>