Update book.json version to 1.27

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>

Author: mdkinney

book.json

@@ -2,7 +2,7 @@
   "variables" : {
     "draft"   : "yes",
     "title"   : "EDK II Package Declaration (DEC) File Format Specification",
-    "version" : "Revision 1.26"
+    "version" : "Revision 1.27"
   },
 
   "plugins": ["puml"],