A little description about not showing characters when you type passwords, which always confuses people

implemented partially from [1]

[1] https://gerrit.wikimedia.org/r/#/c/79730/4/pywikibot/login.py

Change-Id: I6569fcb244f2bb19e6e6b34cc769c187a0e1b2eb
Merge "A little description about not showing characters when you type passwords, which always confuses people"