Updated some old attrs in eample to current versions. But …

… this begs the question, “why didn’t 'make validate' catch these errors earlier?”, to which I do not have an answer at the moment.

P5/Source/Guidelines/en/CMC-ComputerMediatedCommunication.xml

@@ -382,10 +382,10 @@ See the file COPYING.txt for details.
             synch="#tweetsbcrn18.t002" xml:id="cmc_post_1043769240136880128">
             <ptr type="retweet" target="#cmc_post_1043767827927388160"/>
           </post>
-          <post mode="written" creation="human" type="tweet" who="#u3" synch="#tweetsbcrn18.t002"
+          <post modalisty="written" generatedBy="human" type="tweet" who="#u3" synch="#tweetsbcrn18.t002"
             xml:lang="de" xml:id="cmc_post_1043767827927388160">
-            <time creation="system"> 12:43 </time>
-            <figure type="image" creation="human">
+            <time generatedBy="system"> 12:43 </time>
+            <figure type="image" generatedBy="human">
               <graphic url="https://pbs.twimg.com/media/Dnw1TRNXgAAKqlK.jpg:large"/>
             </figure>
           </post>