Correct lvm_type default value in config doc
According to code the default value of lvm_type should be "auto".
- (Integer) If >0, create LVs with multiple mirrors. Note that this requires lvm_mirrors + 2 PVs with available space
* - ``lvm_suppress_fd_warnings`` = ``False``
- (Boolean) Suppress leaked file descriptor warnings in LVM commands.
- * - ``lvm_type`` = ``default``
+ * - ``lvm_type`` = ``auto``
- (String) Type of LVM volumes to deploy; (default, thin, or auto). Auto defaults to thin if thin is supported.
* - ``volume_group`` = ``cinder-volumes``
- (String) Name for the VG that will contain exported volumes
