Bump version
Fix typo
Add more words to the spelling whitelist
v0.21

    - The 198.51.100.0/24 and 203.0.113.0/24 networks were mistakenly put in
      the unroutable list, rather than the testnet list. This has been
      fixed. Note that if you've just been using is_public_ipv4 in your code,
      there are no changes in the results.
    - Added the 6to4 anycast network - 192.88.99.0/24. Addresses in this
      network are not considered public and there is now a new
      is_anycast_ipv4() subroutine exported.
    - Added a number of missing reserved IPv6 networks. These are the
      IPv4-mapped block (::ffff:0:0/96), the discard prefix (100::/64), TEREDO
      (2001::/32), ORCHID (2001:10::/28), and documentation (2001:db8::/32)
      IPv6 networks. There are now is_ipv4_mapped_ipv6(), is_discard_ipv6(),
      is_teredo_ipv6(), is_orchid_ipv6(), and is_documentation_ipv6()
      subs. Note that the TEREDO and ORCHID networks are both subnets of the
      larger special network, and as such were already excluded by
      is_public_ipv6(), though arguably the TEREDO addresses _should_ be
      considered public.
    - Rewrote most of the docs to greatly reduce the amount of text and to
      improve the ToC on MetaCPAN and search.cpan.org.