Add known changes for 2.6.2.

CHANGELOG.rdoc

+== 2.6.2
+* Retain the current annotate block unless --force is specified
+* Always load models, since they may not be autoloaded by Rails
+* The pg array type is now detected (see #158)
+
 == 2.6.0.beta2
 
 * support for composite_primary_keys (garysweaver)