luci-app-attendedsysupgrade: Rewrite README.md

Signed-off-by: Bruxism <38876789+Bruxism@users.noreply.github.com>

Author: Bruxism

applications/luci-app-attendedsysupgrade/README.md

@@ -1,15 +1,29 @@
 # luci-app-attendedsysupgrade
 
-This app adds OpenWrt firmware upgrade and update as well as package update 
-functionality via its web interface.
+`luci-app-attendedsysupgrade` is a plugin for the OpenWrt LuCI web interface
+that facilitates updates and upgrades for both firmware and software packages. 
 
-When activated, this app sends a build request that includes system CPU
-architecture/target and currently installed packages to an 
-*Attended SysUpgrade server* (ASU) which, if available, will then respond 
-with an install-ready custom image that includes firmware and package updates.
+Upon installation, it adds a web page to the OpenWrt LuCI web interface
+available at `System > Attended Sysupgrade` which provides controls
+and configurations for when and where to send build requests.
+
+Build requests include information about the request system's 
+CPU architecture/target and its currently installed packages. These are sent
+to an _**A**ttended **S**ys**U**pgrade_ server (ASU) which,
+if available, will then respond with an install-ready custom firmware image that
+includes the latest requested firmware and package updates.
+
+_An option in the configuration page called "Advanced Mode" activates a prompt 
+to customize what to include upon a manually-activated build request._
+
+Following a successful build request, the user is prompted with a link to
+download a copy of the custom firmware image to their computer and the option to
+immediately install the custom firmware image either with or without keeping
+currently set system configurations.
 
 The process per image takes between 30 seconds and 5 minutes, and may be down
-for a few days during the build rollouts and peak use following major upgrades.
+for a few days during the build rollouts and peak usage that follows major
+OpenWrt upgrades.
 
 More information on the backend server and how to host one are available on the
 projects page: https://github.com/openwrt/asu