MEN-2248: Document missing options in the scripts

Changelog: Title

Signed-off-by: Lluis Campos <lluis.campos@northern.tech>

convert-stage-4.sh

@@ -9,7 +9,7 @@ Usage: $0 [options]
 
     Options: [-m|--mender-disk-image | -g|--mender-client | -a|--artifact-name |
               -d|--device-type | -p|--demo-host-ip | -u| --server-url |
-              -t| --tenant-token]
+              -c|--server-cert -t| --tenant-token -k|--keep -h|--help]
 
         --mender-disk-image - Mender raw disk image
         --mender-client     - Mender client binary file
@@ -18,6 +18,9 @@ Usage: $0 [options]
         --demo-host-ip      - Mender demo server IP address
         --server-url        - Mender production server url
         --server-cert       - Mender server certificate
+        --tenant-token      - Mender tenant token
+        --keep              - Keep intermediate files in output directory
+        --help              - Show help and exit
 
     Examples:
 

mender-convert

@@ -36,7 +36,7 @@ Options: [-r|--raw-disk-image | -m|--mender-disk-image | -s|--data-part-size-mb
           -d|--device-type | -p|--rootfs-partition-id | -i|--demo-host-ip |
           -c|--server-cert | -u|--server-url | -t|--tenant-token |
           -g|--mender-client | -b|--bootloader-toolchain | -a|--artifact-name |
-          -e|--storage-total-size-mb | -k|--keep | -v|--version]
+          -e|--storage-total-size-mb | -k|--keep | -v|--version -h|--help]
 
         raw-disk-image        - raw disk embedded Linux (Debian, Raspbian,
                                 Ubuntu, etc.) image path
@@ -58,6 +58,7 @@ Options: [-r|--raw-disk-image | -m|--mender-disk-image | -s|--data-part-size-mb
                                 it is used to calculate the rootfs final size
         keep                  - keep intermediate files in output directory
         version               - print the version
+        help                  - show help and exit
 
         Note: root filesystem size used in Mender image creation can be found as
               an output from 'raw-disk-image-shrink-rootfs' command or, in case