Typo in german translation

[felix . ostmann]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I../. -I.././include -I.././lib  -Wdate-time 
-D_FORTIFY_SOURCE=2 -g -O2 -fdebug-prefix-map=/build/bash-7fckc0/bash-4.4=. 
-fstack-protector-strong -Wformat -Werror=format-security -Wall -no-pie 
-Wno-parentheses -Wno-format-security
uname output: Linux www44 4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u5 
(2017-09-19) x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.4
Patch Level: 12
Release Status: release

Description:
    There is a typo in the german .po-file: as should be als
    ./po/de.po-msgid "filename argument required"
    ./po/de.po:msgstr "Ein Dateiname wird as Argument benötigt."

Repeat-By:
    call source without a filename

    $ LANG=de_DE.utf8 source
    -bash: source: Ein Dateiname wird as Argument benötigt.
    source: Aufruf: source Dateiname [Argumente]

Fix:
    ./po/de.po-msgid "filename argument required"
    ./po/de.po:msgstr "Ein Dateiname wird als Argument benötigt."