fix dangling keyfunc examples in documentation of heapq and sorted (GH-1432)

* fix dangling mention of key=str.lower in heapq doc

* Fix dangling mention of keyfunc example for sorted()
(cherry picked from commit 6bdb6f7675922e601e742758c7c240a751fd365b)

Co-authored-by: Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de>
2 files changed