Documentation: Fix debian package locations / dependencies.

Fixes #5566

doc/2.3-setting-up-ido.md

@@ -14,6 +14,12 @@ both MySQL and PostgreSQL is implemented.
 > Icinga 1.x and therefore require manual upgrade steps during pre-final
 > milestone releases.
 
+> **Tip**
+>
+> Only install the IDO feature if your web interface or reporting tool requires
+> you to do so (for example, [Icinga Web](#setting-up-icinga-web) or [Icinga Web 2](#setting-up-icingaweb2)).
+> [Icinga Classic UI](#setting-up-icinga-classic-ui) does not use IDO as backend.
+
 ### <a id="configuring-ido-mysql"></a> Configuring IDO MySQL
 
 #### <a id="setting-up-mysql-db"></a> Setting up the MySQL database
@@ -50,6 +56,9 @@ following command:
 >
 > On SuSE-based distributions the schema files are installed in
 > `/usr/share/doc/packages/icinga2-ido-mysql/schema`.
+>
+> The Debian/Ubuntu packages put the schema files into
+> `/usr/share/icinga2-ido-mysql/schema`.
 
 #### <a id="upgrading-mysql-db"></a> Upgrading the MySQL database
 
@@ -152,6 +161,9 @@ using the following command:
 >
 > On SuSE-based distributions the schema files are installed in
 > `/usr/share/doc/packages/icinga2-ido-pgsql/schema`.
+>
+> The Debian/Ubuntu packages put the schema files into
+> `/usr/share/icinga2-ido-pgsql/schema`.
 
 
 #### <a id="upgrading-postgresql-db"></a> Upgrading the PostgreSQL database

doc/2.4-setting-up-livestatus.md

@@ -4,6 +4,13 @@ The [MK Livestatus](http://mathias-kettner.de/checkmk_livestatus.html) project
 implements a query protocol that lets users query their Icinga instance for
 status information. It can also be used to send commands.
 
+> **Tip**
+>
+> Only install the Livestatus feature if your web interface or addon requires
+> you to do so (for example, [Icinga Web 2](#setting-up-icingaweb2)).
+> [Icinga Classic UI](#setting-up-icinga-classic-ui) and [Icinga Web](#setting-up-icinga-web)
+> do not use Livestatus as backend.
+
 The Livestatus component that is distributed as part of Icinga 2 is a
 re-implementation of the Livestatus protocol which is compatible with MK
 Livestatus.

doc/2.5-setting-up-icinga2-uis.md

@@ -13,6 +13,11 @@ statusmap parents are available through intelligent compatibility layers
 for dumping the host dependencies as parents.
 Special restrictions are noted specifically in the sections below.
 
+> **Tip**
+>
+> Chose your preferred interface. There's no need to install [Classic UI](#setting-up-icinga-classic-ui)
+> if you prefer [Icinga Web](#setting-up-icinga-web) or [Icinga Web 2](#setting-up-icingaweb2) for example.
+
 ### <a id="setting-up-icinga-classic-ui"></a> Setting up Icinga Classic UI
 
 Icinga 2 can write `status.dat` and `objects.cache` files in the format that
@@ -30,6 +35,11 @@ the Classic UI using the following packages:
   Debian        | icinga2-classicui
   all others    | icinga2-classicui-config icinga-gui
 
+> **Note**
+>
+> Debian packages require additional dependencies satisfied by the [debmon](http://www.debmong.org)
+> repository.
+
 > **Note**
 >
 > On all distributions other than Debian you may have to restart both your web