Index slangs and compile-time variables, fixing gh #556

Author: pdl

doc/Language/variables.pod6

@@ -397,6 +397,8 @@ Note: Slangs are NYI in Rakudo.
 The C<~> twigil is for referring to sublanguages (called slangs). The
 following are useful:
 
+X<|$~MAIN>X<|$~Quote>X<|$~Quasi>X<|$~Regex>X<|$~Trans>X<|$~P5Regex>
+
     $~MAIN       the current main language (e.g. Perl statements)
     $~Quote      the current root of quoting language
     $~Quasi      the current root of quasiquoting language
@@ -1055,6 +1057,8 @@ the block to the caught exception.
 
 =head2 Compile-time variables
 
+X<|$?FILE>X<|$?LINE>X<|::?CLASS>X<|&?ROUTINE>X<|&?BLOCK>X<|%?LANG>X<|%?RESOURCES>
+
 =for table
     $?FILE         Which file am I in?
     $?LINE         Which line am I at?
@@ -1066,6 +1070,8 @@ the block to the caught exception.
 
 Other compile-time variables:
 
+X<|$?SCOPE>X<|$?PACKAGE>X<|$?MODULE>X<|$?CLASS>X<|$?ROLE>X<|$?GRAMMAR>X<|$?TABSTOP>X<|$?USAGE>X<|$?ENC>
+
 =for table
     $?SCOPE     Which lexical scope am I in?
     $?PACKAGE   Which package am I in?