Improve docs

doc/helgobox/modules/ROOT/nav.adoc

@@ -1,6 +1,5 @@
 * xref:introduction.adoc[]
 * xref:installation.adoc[]
-* xref:usage.adoc[]
 * xref:plug-in.adoc[]
 ** xref:plug-in/user-interface.adoc[]
 * xref:app.adoc[]

doc/helgobox/modules/ROOT/pages/app.adoc

@@ -1,3 +1,4 @@
 = Helgobox App
 
-See xref:app/user-interface.adoc[].
+[quote]
+include::partial$app-desc.adoc[]

doc/helgobox/modules/ROOT/pages/installation.adoc

@@ -9,7 +9,7 @@ ReaPack is a popular 3rd-party package manager for REAPER that makes installing
 
 Please check below system requirements before attempting to install Helgobox!
 
-TIP: A more detailed compatibility table can be found link:https://www.helgoboss.org/projects/helgobox#requirements[here].
+NOTE: A more detailed compatibility table can be found link:https://www.helgoboss.org/projects/helgobox#requirements[here].
 
 [[windows]]
 === Windows

doc/helgobox/modules/ROOT/pages/introduction.adoc

@@ -1,8 +1,12 @@
 = Introduction
 
-link:https://www.helgoboss.org/projects/helgobox[Helgobox] is an instrument plug-in for link:https://www.reaper.fm[REAPER] that unites the products link:https://www.helgoboss.org/projects/realearn[ReaLearn] and link:https://www.helgoboss.org/projects/playtime[Playtime] under one roof.
+link:https://www.helgoboss.org/projects/helgobox[Helgobox] is an add-on for link:https://www.reaper.fm[REAPER] that unites the products link:https://www.helgoboss.org/projects/realearn[ReaLearn] and link:https://www.helgoboss.org/projects/playtime[Playtime] under one roof.
 
-In addition to the plug-in, it comes with the xref:app.adoc[], a modern user interface for the Helgobox Instrument.
-It runs embedded in REAPER and in the future also as a separate mobile app (iOS, Android).
+It consists of two components:
 
-If you want to learn more about the contained products, please refer to the link:https://docs.helgoboss.org/realearn[ReaLearn Reference] or link:https://docs.helgoboss.org/playtime[Playtime Reference].
+xref:plug-in.adoc[]::
+include::partial$plug-in-desc.adoc[]
+xref:app.adoc[]::
+include::partial$app-desc.adoc[]
+
+include::partial$product-specific-info.adoc[]

doc/helgobox/modules/ROOT/pages/plug-in.adoc

@@ -1,3 +1,17 @@
-= Helgobox Instrument Plug-In
+= Helgobox Plug-In
 
-See xref:plug-in/user-interface.adoc[]
+[quote]
+include::partial$plug-in-desc.adoc[]
+
+The plug-in is fired up just like any other VST instrument in REAPER: By adding an instance of it to an FX chain:
+
+. Right-click the empty space in REAPER's track control panel
+. Select menu:Insert virtual instrument on new track...[]
+. Double-click entry "VSTi: Helgobox - ReaLearn & Playtime (Helgoboss)"
+
+Initially, you see the xref:plug-in/user-interface.adoc[plug-in window].
+From there you can open the xref:app/user-interface.adoc[Helgobox App].
+
+include::partial$product-specific-info.adoc[]
+
+It is complemented by the xref:app.adoc[].

doc/helgobox/modules/ROOT/pages/plug-in/user-interface.adoc

@@ -1,6 +1,8 @@
 = User interface
 
-The Helgobox instrument plug-in's user interface primarily provides the user interface for link:https://www.helgoboss.org/projects/realearn[ReaLearn]. Refer to the xref:realearn::user-interface.adoc[] section of the ReaLearn Reference for details.
+The plug-in's native user interface features a plain and simple design.
+It is home to link:https://www.helgoboss.org/projects/realearn[ReaLearn], the controller integration tool of Helgobox.
+Refer to the xref:realearn::user-interface.adoc[ReaLearn user interface documentation] to learn more about it!
 
 .Plug-in window
 image::screenshots/plugin-window.png[]

doc/helgobox/modules/ROOT/partials/app-desc.adoc

@@ -0,0 +1,2 @@
+A complement to the xref:plug-in.adoc[] which provides a modern user interface.
+It runs embedded in REAPER and in the future also as a separate mobile app (iOS, Android).

doc/helgobox/modules/ROOT/partials/plug-in-desc.adoc

@@ -0,0 +1 @@
+A VST instrument plug-in that deeply integrates with REAPER by using its link:https://www.reaper.fm/sdk/plugin/plugin.php[Plug-in Extensions] mechanism.

doc/helgobox/modules/ROOT/partials/product-specific-info.adoc

@@ -0,0 +1 @@
+For product-specific information, please consult the link:https://docs.helgoboss.org/realearn[ReaLearn Reference] or link:https://docs.helgoboss.org/playtime[Playtime Reference].