2012-04-04 wenzelm 2012-04-04 removed obsolete isar-overview manual;
2012-04-03 wenzelm 2012-04-03 formal integration of "prog-prove" manual; "main" is a reference manual;
2010-05-14 blanchet 2010-05-14 added Sledgehammer manual; some material was recovered from the Isar material, the rest is new
2009-10-22 blanchet 2009-10-22 Added Nitpick manual.
2009-03-11 nipkow 2009-03-11 Added "What's in Main" to doc sources
2009-03-03 haftmann 2009-03-03 more canonical directory structure of manuals
2009-02-15 wenzelm 2009-02-15 explicit section for old/outdated manuals, which are still informative to some extent;
2008-07-02 wenzelm 2008-07-02 renamed Contents to Dirs to avoid case-conflict with doc/Contents;