Add comment for translators

translation/source/study.xml

@@ -103,7 +103,7 @@
   <string name="loadAPositionFromFen">Load a position from FEN</string>
   <string name="loadAGameFromPgn">Load games from PGN</string>
   <string name="automatic">Automatic</string>
-  <plurals name="pasteYourPgnTextHereUpToNbGames">
+  <plurals name="pasteYourPgnTextHereUpToNbGames" comment="It is possible to create multiple chapters in one go. Please try to convey this using a short translation.">
     <item quantity="one">Paste your PGN text here, up to %s game</item>
     <item quantity="other">Paste games as PGN text here. For each game, a new chapter is created. The study can have up to %s chapters.</item>
   </plurals>