[boost] [type_erasure][docs]uniform term for underlying

The doc: http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/... uses 3 terms: underlying actual contained to designate, essentially, the same thing, the actual type stored in the any. The docs would be clearer if a uniform term were used, with possibly a link to some glossary where the term was defined. -regards, Larry