added a few missing \versionadded{2.3} tags

Doc/lib/libmodulefinder.tex

@@ -5,6 +5,8 @@
 \declaremodule{standard}{modulefinder}
 \modulesynopsis{Find modules used by a script.}
 
+\versionadded{2.3}
+
 This module provides a \class{ModuleFinder} class that can be used to
 determine the set of modules imported by a script.
 \code{modulefinder.py} can also be run as a script, giving the

Doc/lib/libpickletools.tex

@@ -3,6 +3,8 @@
 \declaremodule{standard}{pickletools}
 \modulesynopsis{Contains extensive comments about the pickle protocols and pickle-machine opcodes, as well as some useful functions.}
 
+\versionadded{2.3}
+
 This module contains various constants relating to the intimate
 details of the \refmodule{pickle} module, some lengthy comments about
 the implementation, and a few useful functions for analyzing pickled

Doc/lib/libstringprep.tex

@@ -6,6 +6,8 @@
 \moduleauthor{Martin v. L\"owis}{martin@v.loewis.de}
 \sectionauthor{Martin v. L\"owis}{martin@v.loewis.de}
 
+\versionadded{2.3}
+
 When identifying things (such as host names) in the internet, it is
 often necessary to compare such identifications for
 ``equality''. Exactly how this comparison is executed may depend on