Specify that the input file shall be UTF-8

Author: jerboaa

src/jdk.jlink/share/classes/jdk/tools/jlink/resources/plugins.properties

@@ -39,14 +39,16 @@ release-info.argument=<file>|add:<key1>=<value1>:<key2>=<value2>:...|del:<key li
 
 release-info.description=\
 <file> option is to load release properties from the supplied file.\n\
+\       The specified file is expected to be encoded in UTF-8.\n\
 add: is to add properties to the 'release' file.\n\
 Any number of <key>=<value> pairs can be passed.\n\
 del: is to delete the list of keys in release file.
 
 release-info.usage=\
 \  --release-info <file>|add:<key1>=<value1>:<key2>=<value2>:...|del:<key list>\n\
 \                            <file> option is to load release properties from\n\
-\                            the supplied file.\n\
+\                            the supplied file. The specified file is expected\n\
+\                            to be encoded in UTF-8.\n\
 \                            add: is to add properties to the 'release' file.\n\
 \                            Any number of <key>=<value> pairs can be passed.\n\
 \                            del: is to delete the list of keys in release file.