RFE #1670167: fix in isinstance() docs.
diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index c38e9fc..02d07a9 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -567,8 +567,9 @@
\begin{funcdesc}{isinstance}{object, classinfo}
Return true if the \var{object} argument is an instance of the
\var{classinfo} argument, or of a (direct or indirect) subclass
- thereof. Also return true if \var{classinfo} is a type object and
- \var{object} is an object of that type. If \var{object} is not a
+ thereof. Also return true if \var{classinfo} is a type object
+ (new-style class) and \var{object} is an object of that type or of a
+ (direct or indirect) subclass thereof. If \var{object} is not a
class instance or an object of the given type, the function always
returns false. If \var{classinfo} is neither a class object nor a
type object, it may be a tuple of class or type objects, or may