Before renaming, Python 3 filenames were 'learnpython3*.py'.
This commit removes the '3' part from the filename.
To verify that the filenames were named consistently across
translations prior to this commit, and to change this:
```
ack -H 'filename:' python.html.markdown
find . -name "python-*.markdown" -exec ack -H 'filename:' {} \;
sed -i 's/^filename: learnpython3/filename: learnpython/' \
python.html.markdown
find . -name "python-*.markdown" -exec \
sed -i 's/^filename: learnpython3/filename: learnpython/' {} \;
```
```
for f in $(find . -iname "*python*" | grep -vE 'python3|git|statcomp'); do
flegacy=$(echo "$f" | sed 's/python/pythonlegacy/')
git mv "$f" "$flegacy"
done
```
Translation typo in comments for slice syntax with omitted indexes:
"Omit the beginning" meant omit the beginning *of the list* (not the beginning of the range)
"Omit the end" meant omit the end *of the list* (not the end of the range)
