Minor cosmetic tweaks.

* create: Adjust indentation and log message.
* README (Installation): Adjust ./configure invokation to work out of
the box.

README

@@ -29,7 +29,7 @@ Behind the scenes, this is a simple wrapper for 'guix system vm-image'.
 
 Installation:
 
-  $ ./configure --with-os-dir=/srv/ganeti/os --sysconfdir=/etc
+  $ ./configure --sysconfdir=/etc --localstatedir=/var
   $ make && sudo make install
 
 Dependencies:

create

@@ -24,7 +24,7 @@ GUIX_PULL_PROFILE="${GUIXPROFILEDIR}/${INSTANCE_NAME}"
 trap "rm -f $CONFIG_FILE" EXIT INT TERM
 
 if [ ! -d "$CACHE_DIR" ]; then
-  mkdir -p "$CACHE_DIR"
+    mkdir -p "$CACHE_DIR"
 fi
 # Make Guix use the specified CACHE_DIR.
 export XDG_CACHE_HOME=$CACHE_DIR
@@ -50,17 +50,17 @@ $GUIX --version
 # be mistaken for commands, so gibberize it through base64.
 # TODO: Support plain text for API users.
 if [ -n "$OSP_CONFIG" ]; then
-  echo "${OSP_CONFIG}" | base64 -di > $CONFIG_FILE
+    echo "${OSP_CONFIG}" | base64 -di > $CONFIG_FILE
 else
-  # If no configuration file was provided, use a default one.
-  cp -L $DEFAULT_CONFIG $CONFIG_FILE
+    log_error "No configuration provided, using ${DEFAULT_CONFIG}."
+    cp -L $DEFAULT_CONFIG $CONFIG_FILE
 fi
 
 if [ -b $TARGET_DEVICE ]; then
-  DEVICE_SIZE=$($BLOCKDEV --getsize64 $TARGET_DEVICE)
+    DEVICE_SIZE=$($BLOCKDEV --getsize64 $TARGET_DEVICE)
 else
-  # Not a real block device.  Assume file disk and just use 'du'.
-  DEVICE_SIZE=$(du --bytes $TARGET_DEVICE)
+    # Not a real block device.  Assume file disk and just use 'du'.
+    DEVICE_SIZE=$(du --bytes $TARGET_DEVICE)
 fi
 
 # Pull the user-specified Guix version, if applicable.