Made GitHubs PRs linkable in the changes.

Not sure about the syntax, though, e.g. if to use GHPR(+GHI) as "system" vs. GH only and using "pull/XY" ("issues/XY") as the actual issue.
diff --git a/pom.xml b/pom.xml
index 0413e80..fe1cccc 100644
--- a/pom.xml
+++ b/pom.xml
@@ -391,7 +391,10 @@
 					</reportSet>
 				</reportSets>
 				<configuration>
-					<issueLinkTemplate>%URL%/browse/%ISSUE%</issueLinkTemplate>
+					<issueLinkTemplatePerSystem>
+						<GHPR>https://github.com/apache/logging-log4cxx/pull/%ISSUE%</GHPR>
+						<JIRA>%URL%/%ISSUE%</JIRA>
+					</issueLinkTemplatePerSystem>
 				</configuration>
 			</plugin>
 		</plugins>
diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index a37af94..94fd8d3 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -107,9 +107,10 @@
 			<action issue="LOGCXX-262" type="fix">socketappendertestcase and xmlsocketappendertestcase not run</action>
 			<action issue="LOGCXX-249" type="fix">Console appender crashes if layout is not set</action>
 
-			<action type="add">Added support for building log4cxx as a statically linked library on Windows. (https://github.com/apache/logging-log4cxx/pull/21)</action>
-			<action type="add">Replaced ant build with cmake. (https://github.com/apache/logging-log4cxx/pull/14)</action>
-			<action type="add">JSONLayout (https://github.com/apache/logging-log4cxx/pull/13)</action>
+			<action issue="21" system="GHPR" type="add">Added support for building log4cxx as a statically linked library on Windows.</action>
+			<action issue="14" system="GHPR" type="add">Replaced ant build with cmake.</action>
+			<action issue="13" system="GHPR" type="add">JSONLayout</action>
+
 			<action type="update">Behavior of StringHelper::startsWith and endsWith synced.</action>
 			<action type="update">Documented C (class) and M (method) log format keywords.</action>
 			<action type="add">LocationInfo for Borland C++ Builder and successors improved.</action>