docs: avoid using adoc syntax that's incompatible with po4a 0.66

Author: SebKuzminsky

docs/src/ladder/ladder-intro.adoc

@@ -11,7 +11,6 @@ released under the LGPL. It was written by Marc Le Douarain.
 
 He describes the beginning of the project on his website:
 
-[quote,Marc Le Douarain, from "Genesis" at the Classic Ladder website]
 _____________________________________________________________________
 I decided to program a ladder language only for test purposes at the
 start, in February 2001. It was planned, that I would have to
@@ -27,6 +26,8 @@ with more complex elements: timer, multiples rungs, etc...
 
 Voila, here is this work... and more: I've continued to add features
 since then.
+
+-- Marc Le Douarain, from "Genesis" at the Classic Ladder website
 _____________________________________________________________________
 
 Classic Ladder has been adapted to work with LinuxCNC's HAL, and is