Update help for generate

Author: Mrunal Patel

README.md

@@ -21,3 +21,39 @@ GLOBAL OPTIONS:
    --version, -v        print the version
 
 ```
+
+Generate
+
+```
+# ocitools generate --help
+NAME:
+   generate - generate a OCI spec file
+
+USAGE:
+   command generate [command options] [arguments...]
+
+OPTIONS:
+   --rootfs                                             path to the rootfs
+   --read-only                                          make the container's rootfs read-only
+   --privileged                                         enabled privileged container settings
+   --hostname "acme"                                    hostname value for the container
+   --uid "0"                                            uid for the process
+   --gid "0"                                            gid for the process
+   --groups [--groups option --groups option]           supplementary groups for the process
+   --cap-add [--cap-add option --cap-add option]        add capabilities
+   --cap-drop [--cap-drop option --cap-drop option]     drop capabilities
+   --network                                            network namespace
+   --mount                                              mount namespace
+   --pid                                                pid namespace
+   --ipc                                                ipc namespace
+   --uts                                                uts namespace
+   --selinux-label                                      process selinux label
+   --tmpfs [--tmpfs option --tmpfs option]              mount tmpfs
+   --args                                               command to run in the container
+   --env [--env option --env option]                    add environment variable
+   --mount-cgroups "ro"                                 mount cgroups (rw,ro,no)
+   --bind [--bind option --bind option]                 bind mount directories src:dest:(rw,ro)
+   --prestart [--prestart option --prestart option]     path to prestart hooks
+   --poststop [--poststop option --poststop option]     path to poststop hooks
+   --root-propagation                                   mount propagation for root
+```