Add issue links to changelog entries (#2322)

Author: vy

src/changelog/.2.x.x/fix_StatusLogger_instant_formatting.xml

@@ -3,6 +3,7 @@
        xmlns="http://logging.apache.org/log4j/changelog"
        xsi:schemaLocation="http://logging.apache.org/log4j/changelog https://logging.apache.org/log4j/changelog-0.1.3.xsd"
        type="fixed">
+  <issue id="2322" link="https://github.com/apache/logging-log4j2/pull/2322"/>
   <description format="asciidoc">
     Add `log4j2.StatusLogger.DateFormatZone` system property to set the time-zone `StatusLogger` uses to format `java.time.Instant`.
     Without this formatting patterns accessing to time-zone-specific fields (e.g., year-of-era) cause failures.

src/changelog/.2.x.x/fix_StatusLogger_stack_overflow.xml

@@ -3,5 +3,6 @@
        xmlns="http://logging.apache.org/log4j/changelog"
        xsi:schemaLocation="http://logging.apache.org/log4j/changelog https://logging.apache.org/log4j/changelog-0.1.3.xsd"
        type="fixed">
+  <issue id="2322" link="https://github.com/apache/logging-log4j2/pull/2322"/>
   <description format="asciidoc">Fix stack overflow in `StatusLogger`</description>
 </entry>