Fix Javadoc

Fix Javadoc for method
org.apache.logging.log4j.core.filter.StringMatchFilter.Builder.setMatchString(String)

Author: garydgregory

log4j-core/src/main/java/org/apache/logging/log4j/core/filter/StringMatchFilter.java

@@ -240,9 +240,9 @@ public static class Builder extends AbstractFilterBuilder<StringMatchFilter.Buil
         private String text = "";
 
         /**
-         * Sets the text to match.
-         * @param text the text to match.
-         * @return this
+         * Sets the text to search in event messages.
+         * @param text the text to search in event messages.
+         * @return this instance.
          */
         public StringMatchFilter.Builder setMatchString(final String text) {
             this.text = text;