man: improve description of the tool

Add the tool's flow into the manpage.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1521040

man/ovirt-engine-hyper-upgrade.8

@@ -1,12 +1,30 @@
 .TH man 8 "18 Oct, 2017" "ovirt-engine-hyper-upgrade man page"
 .SH NAME
-ovirt-engine-hyper-upgrade \- A tool to help users upgrade RHV Manager
+ovirt-engine-hyper-upgrade \- A tool to help users upgrade RHV Manager (RHVM)
 .SH SYNOPSIS
 ovirt-engine-hyper-upgrade.py [-h] [--backup] [--backup-dir BACKUP_DIR]
                                   [--upgrade-to-rhv UPGRADE_TO_RHV]
 
 .SH DESCRIPTION
-\fBovirt-engine-hyper-upgrade\fP is a command line tool to manage upgrades for RHV Manager.
+The \fBovit-engine-hyper-upgrade\fP is a wrapper tool to automate RHV Manager upgrades.
+
+First, the tool detects the current version of RHVM running on the system and check if there are updates
+.br
+available related to minor version detected. If there are updates available, update all ovirt-engine-*setup
+.br
+packages via yum and execute engine-setup to complete the update. After the update is completed, update the
+.br
+entire system via yum update command.
+
+Second stage, all system is up to date, enable the new channels required for the next major release via
+.br
+subscription-manager and update all ovirt-engine-*setup packages. As soon the packages are updated,
+.br
+execute engine-setup to complete the major upgrade.
+
+Final stage, as new channel were added into the system, execute, yum update, to have the system
+.br
+up to date and disable previous major versions related channels not required anymore.
 .P
 
 .TP