Adding back HISTORY as a parent of TAU-DATABASE.

git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2290 303c5b2c-9740-0410-b014-fd8f9db7be32
Fixing a couple typos

git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2291 303c5b2c-9740-0410-b014-fd8f9db7be32
Fixing a typo

git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2292 303c5b2c-9740-0410-b014-fd8f9db7be32