update encoding

erddap/content/setup.xml

@@ -86,7 +86,7 @@ You should only use "plaintext" or "MD5" if you need to match values stored
 that way in an external password database.
 See the info at http://coastwatch.pfeg.noaa.gov/erddap/download/setup.html#security
 -->
-  <passwordEncoding>UEPMD5</passwordEncoding>
+  <passwordEncoding>SHA256</passwordEncoding>
 
   <!-- This determines whether datasets that the user doesn't currently have access to
 (because he isn't logged in or because his roles don't allow access)