dtd/rng: Replace update type 'bug' with 'critical'

pisi-spec.dtd

@@ -132,7 +132,7 @@ suck anyway -->
 
 <!ELEMENT Update (#PCDATA | Date | Version | Comment | Type | Requires | Name | Email)*>
 <!ATTLIST Update release CDATA #REQUIRED>
-<!ATTLIST Update type (security|bug) #IMPLIED>
+<!ATTLIST Update type (critical|security) #IMPLIED>
 
 <!ELEMENT Date (#PCDATA)>
 <!ELEMENT Version (#PCDATA)>

pisi-spec.rng

@@ -1577,8 +1577,8 @@
         <optional>
             <attribute name="type">
                 <choice>
+                    <value>critical</value>
                     <value>security</value>
-                    <value>bug</value>
                 </choice>
             </attribute>
         </optional>