Update pacman.conf to pacman-6.0.0-2

As suggested by xatier on GitHub:
* #41
* https://github.com/archlinux/archlinux-docker/pull/42/files

pacman.conf

@@ -16,10 +16,9 @@
 #GPGDir      = /etc/pacman.d/gnupg/
 #HookDir     = /etc/pacman.d/hooks/
 #HoldPkg     = pacman glibc
-#XferCommand = /usr/bin/curl -C - -f %u > %o
+#XferCommand = /usr/bin/curl -L -C - -f -o %o %u
 #XferCommand = /usr/bin/wget --passive-ftp -c -O %o %u
 #CleanMethod = KeepInstalled
-#UseDelta    = 0.7
 Architecture = auto
 
 # Pacman won't upgrade packages listed in IgnorePkg and members of IgnoreGroup
@@ -32,9 +31,10 @@ Architecture = auto
 # Misc options
 #UseSyslog
 #Color
-#TotalDownload
+#NoProgressBar
 CheckSpace
 #VerbosePkgLists
+#ParallelDownloads = 5
 
 # By default, pacman accepts packages signed by keys that its local keyring
 # trusts (see pacman-key and its man page), as well as unsigned packages.
@@ -69,21 +69,30 @@ LocalFileSigLevel = Optional
 # repo name header and Include lines. You can add preferred servers immediately
 # after the header, and they will be used before the default mirrors.
 
+#[testing]
+#Include = /etc/pacman.d/mirrorlist
+
 [core]
 Include = rootfs/etc/pacman.d/mirrorlist
 
 [extra]
 Include = rootfs/etc/pacman.d/mirrorlist
 
+#[community-testing]
+#Include = /etc/pacman.d/mirrorlist
+
 [community]
 Include = rootfs/etc/pacman.d/mirrorlist
 
 # If you want to run 32 bit applications on your x86_64 system,
 # enable the multilib repositories as required here.
 
+#[multilib-testing]
+#Include = /etc/pacman.d/mirrorlist
+
 #[multilib]
 #Include = /etc/pacman.d/mirrorlist
-#
+
 # An example of a custom package repository.  See the pacman manpage for
 # tips on creating your own repositories.
 #[custom]