Document that hub is needed

Bumped version to 1.6.11

1.6.10

* GeoIP_database_info now returns the full version string rather than
  incorrectly truncating it. GitHub #79.
* This API is now distributed with a small test copy of GeoIP.dat rather than
  a full copy.
* Fix issue where Visual Studio 2015 was optimizing out initialization code.
  Reported and fixed by Scott Godin. GitHub #81.
* Fix test/benchmark on Windows. Gisle Vanem. GitHub #75.

Version 1.6.9

Version 1.6.8

Segfault Fix, More Safety Checks, Windows Fixes

* Fixed a MSVC parser stack overflow when parsing `regionName.c` and
 `timeZone.c`. Fix by elliotlo. GitHub #64.
* Updated region codes and timezones.
* When using `GEOIP_MEMORY_CACHE` with an invalid database file, the search
  tree traversal could attempt to read memory outside of the memory allocated
  for the memory cache, resulting in a segmentation fault. A check was added
  to ensure that the traversal code does not try to read beyond the end of the
  file, whether in memory, memory mapped, or on disk.
* Previously the return values from file reads were ignored. We now check
  these values to ensure that there were no errors.

1.6.6

* Replaced usage of deprecated fileno, read, and lseek on Visual Studio 2005+
  with their ISO C++ conformant replacements. (Fix by ClaudiuHKS. GitHub #55.)
* A warning about using a double as a float was fixed. (Fix by ClaudiuHKS.
  GitHub #56.)
* Fixed segfault when doing a lookup on an empty database. (Fix by NesoK.
  GitHub #62.)
* Fixed a memcheck error from valgrind in the `_check_mtime`
  function. (Reported by yurivct. GitHub #60.)
* Fixed `_check_mtime` to check the return value of `gettimeofday` rather than
  just assuming it worked.

1.6.5

* A segmentation fault in `geoiplookup` was fixed when the utility was passed
  an invalid database. (Reported in Red Hat bug #1180874.)
* Additional validation was added for validation of the size used in the
  creation of the index cache. (Based on discussion in Red Hat bug #832913.)
* Changed the code to only look up country codes by using functions which
  ensure that we do not try to look past the end of an array. (Reported by
  Ivan Sorokin. GitHub #53)

1.6.4: Windows and Misc Updates

* Update Fips codes (Boris Zentner)
* Several issues with the MinGW build were fixed. (Thomas Pöchtrager. Github
  #46.)
* Use a constructor in pread.c to ensure the critical section is always
  initialized. (Thomas Pöchtrager. Github #47.)
* Added missing include of `io.h` on Windows. (Thomas Pöchtrager. Github #49.)
* Fixed `configure` warning that `'missing' script is too old or missing`.
  (Reported by Floren Munteanu. Github #33.)
* Previously `nmake /f Makefile.vc clean` would fail on Windows. This was
  fixed.
* Obsolete win32 and NetWare make files were removed.
* Numerous documentation updates. (Reported by Thomas Pöchtrager. GitHub #48.)

Add git push --tags step to release instructions