doc: Correct a few uses of @Qcode macro.

* genpropdoc.m: Use @code rather than @Qcode when property is not quoted.

* plot.txi: Add missing double-quote in @Qcode invocation.

Author: Rik

doc/interpreter/genpropdoc.m

@@ -876,7 +876,7 @@ element defines a pixel with the element (1,1) representing the \
 
       case "clim"
         s.doc = "Define limits for the color axis of __objname__ \
-children that have the @qcode{cdata} property.  \
+children that have the @code{cdata} property.  \
 __modemsg__";
         s.valid = valid_2elvec;
         s.category = "Color and Transparency";
@@ -885,7 +885,7 @@ element defines a pixel with the element (1,1) representing the \
         s.doc = "Current state of the color limit mode, either \
 manually set by the \
 @ref{XREFaxesclim, , @w{@qcode{\"clim\"} property}} or automatically set by \
-Octave to the minimum and maximum @qcode{cdata} values of __objname__'s \
+Octave to the minimum and maximum @code{cdata} values of __objname__'s \
 children.";
         s.category = "Color and Transparency";
 

doc/interpreter/plot.txi

@@ -747,7 +747,7 @@ figure window, call the @code{close} function.
 @subsection Use of the "interpreter" Property
 
 @code{text} (such as titles, labels, legend item) and @code{axes} objects
-feature an @ref{XREFtextinterpreter,,@qcode{"interpreter}} and a
+feature an @ref{XREFtextinterpreter,,@qcode{"interpreter"}} and a
 @ref{XREFaxesticklabelinterpreter,,@qcode{"ticklabelinterpreter"}} property
 respectively.  It determines the manner in which special control sequences in
 the text are rendered.