Fix broken links in 'History, mission and community' section

There are a number of old links in the History, mission and community (should that page path have a capital letter in it?):

• Two links on http://drupal.org/node/21779 should be changed to use /node/ instead of /book/view/
• Links on http://drupal.org/node/22957 should be changed to use /node/ instead of /node/view/