Pass changes.xml thru xmllint when generating CHANGES and CHANGES.ru.
diff --git a/docs/dtd/changes.dtd b/docs/dtd/changes.dtd
index 4dea2c7..e14518a 100644
--- a/docs/dtd/changes.dtd
+++ b/docs/dtd/changes.dtd
@@ -12,10 +12,10 @@
>
<!ELEMENT change (para)* >
-<!ATTLIST change type (bugfix | feature | change | workaround) #IMPLIED >
+<!ATTLIST change type (bugfix | feature | change | security | workaround) #IMPLIED >
<!ELEMENT para (#PCDATA | at | br | nobr)* >
-<!ATTLIST para lang (ru | en) #IMPLIED >
+<!ATTLIST para lang (ru | en) #REQUIRED >
<!ELEMENT at EMPTY >
<!ELEMENT br EMPTY >