installation: reword/expand/reflow and fix login thumbnail

Try to improve the layout, still not really ideal with that many
thumbnails in a single relatively short section but should be a bit
easier to read.

Change the place of the UI login thumbnail as before the numerical
bulletin point list it won't work due to block boundaries and asciidoc

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

pmg-installation.adoc

@@ -138,7 +138,7 @@ lets you choose the ZFS RAID level and select which disks will be used.
 WARNING: ZFS on top of any hardware RAID is not supported and can result in data
 loss.
 
-[thumbnail="installer/pmg-select-location.png", float="left"]
+[thumbnail="installer/pmg-select-location.png"]
 
 The next page asks for basic configuration options like your
 location, timezone, and keyboard layout. The location is used to
@@ -147,13 +147,13 @@ The installer is usually able to auto-detect these settings, so you only need to
 change them in rare situations when auto-detection fails, or when you want to
 use a keyboard layout not commonly used in your country.
 
-[thumbnail="installer/pmg-set-password.png"]
+[thumbnail="installer/pmg-set-password.png", float="left"]
 
 You then need to specify an email address and the superuser (root)
 password. The password must have at least 5 characters, but we highly
 recommend to use stronger passwords - here are some guidelines:
 
-- Use a minimum password length of 12 to 14 characters.
+- Use a minimum password length of at least 12 characters.
 
 - Include lowercase and uppercase alphabetic characters, numbers and symbols.
 
@@ -169,10 +169,10 @@ example:
 
 - Error messages from periodic cron jobs.
 
-All those notification mails will be sent to the specified email address.
-
 [thumbnail="installer/pmg-setup-network.png"]
 
+All those notification mails will be sent to the specified email address.
+
 The next step is the network configuration. Please note that you can use either
 IPv4 or IPv6 here, but not both. If you want to configure a dual stack node,
 you can easily do that after the installation.
@@ -188,25 +188,38 @@ to the target disk(s).
 
 [thumbnail="installer/pmg-summary.png"]
 
-Copying the packages usually takes several minutes. When this is
-finished, you can reboot the server.
+Copying the packages usually takes several minutes, mostly depending on the
+speed of the installation medium and the target disk performance.
+
+When copying and setting up the packages has finished, you can reboot the
+server. This will be done automatically after a few seconds by default.
+
+.Installation Failure
 
 If the installation failed, check out specific errors on the second TTY
 (`CTRL + ALT + F2') and ensure that the systems meets the
-xref:install_minimal_requirements[minimum requirements]. If the installation
-is still not working, look at the xref:getting_help[how to get help chapter].
+xref:install_minimal_requirements[minimum requirements].
 
-Further configuration is done via the {pmg} web interface:
+If the installation is still not working, look at the xref:getting_help[how to
+get help chapter].
+
+
+Accessing the Management Interface Post-Installation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 [thumbnail="screenshot/pmg-gui-login-window.png"]
 
-. Point your browser to the IP address given during the installation
-(https://youripaddress:8006).
+After a succesful installation and reboot of the system you can use the {pmg}
+web interface for further configuration.
 
-. Log in and upload your subscription key.
-+
-NOTE: The default login is "root", and the password is the one chosen during the
-installation.
+. Point your browser to the IP address given during the installation and port
+  8006, for example: https://youripaddress:8006
+
+. Log in using the `root` username and the password chosen during installation.
+
+. Upload your subscription key to gain access to the Enterprise repository.
+  Otherwise, you will need to set up one of the public, less tested package
+  repositories to get updates for security fixes, bug fixes, and new features.
 
 . Check the IP configuration and hostname.