Two typos of UsersGuide 5.26 on page 196 and 197

Sorry that I have not digged into the mine to confirm whether these typos have been mentioned.

  1. page 196, the 14th line from the bottom:
    "An object can be saved in a tree if a ROOT dictionary for it class has been generated…"
    where “it class” should be “its class”.
  2. page 197, the 8th line from the top:
    "… or it can be a set to a number between 1 and 99 indicating …"
    where the “a” before “set” should be deleted.

Fix done in the new Docbook version.