fix wrong urllib parse function being used to percent encode usernames and passwords, where before spaces would be incorrectly encoded to '+' instead of '%20' which is behaviour for a different usecase

[heymoonman]

The example given for percent-encoding usernames and passwords for a MongoDB URI first mentions .quote() should be used, but proceeds to incorrectly use .quote_plus(), changing spaces to plus signs instead of their percent encoding equivalent.

The example should use .quote() to be clear and exemplify proper use.

[blink1073]

Hi @M-Moon, these examples were changed to handle the case where the username or password contains an unescaped / character, which would get interpreted as the database name. https://jira.mongodb.org/browse/PYTHON-2973. I think the right thing to do is change the examples to use quote(..., safe='')

[heymoonman]

Thanks for the response @blink1073, this makes sense. I was not aware of the issue so thanks for letting me know.

[ShaneHarvey]

In this case the code example is correct but the paragraph is wrong. It should say:

Username and password must be percent-escaped with
:py:func:`urllib.parse.quote_plus`, to be used in a MongoDB URI.

[ShaneHarvey]

@M-Moon thank you for reporting this, I've fixed it in #1193!