Documentation bug for pam_userdb

[James Howe]

The man page for pam_userdb(8) has an incorrect example

> auth sufficient pam_userdb.so icase db=/etc/dbtest.db

should be

> auth sufficient pam_userdb.so icase db=/etc/dbtest

It should also be mentioned in the options that ".db" will be added to the value of db.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: libpam-modules 1.1.8-3.6ubuntu2.18.04.1
ProcVersionSignature: Microsoft 4.4.0-17134.706-Microsoft 4.4.35
Uname: Linux 4.4.0-17134-Microsoft x86_64
ApportVersion: 2.20.9-0ubuntu7.6
Architecture: amd64
Date: Thu May 30 13:33:25 2019
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=C.UTF-8
 SHELL=/bin/bash
SourcePackage: pam
UpgradeStatus: No upgrade log present (probably fresh install)