setup-advanced: Improve discussion of manual instructions.

First, make them even less recommended.  But also, remove the list of
packages at the top -- it's not actually useful.

docs/development/setup-advanced.md

@@ -40,6 +40,10 @@ ignoring the parts about `vagrant` (since you're not using it).
 
 ## Installing manually on Linux
 
+We recommend one of the other installation models, since we test those
+continuously.  But if you know what you're doing and really want to
+install everything manually, these instructions should work.
+
 * [Debian or Ubuntu systems](#on-debian-or-ubuntu-systems)
 * [Fedora 22 (experimental)](#on-fedora-22-experimental)
 * [CentOS 7 Core (experimental)](#on-centos-7-core-experimental)
@@ -47,22 +51,6 @@ ignoring the parts about `vagrant` (since you're not using it).
 * [Fedora/CentOS common steps](#common-to-fedora-centos-instructions)
 * [Steps for all systems](#all-systems)
 
-If you really want to install everything manually, the below instructions
-should work.
-
-Install the following non-Python dependencies:
- * libffi-dev — needed for some Python extensions
- * postgresql 9.1 or later — our database (client, server, headers)
- * memcached (and headers)
- * rabbitmq-server
- * libldap2-dev
- * python3-dev
- * python-dev
- * python-virtualenv
- * redis-server — rate limiting
- * tsearch-extras — better text search
- * libfreetype6-dev — needed before you pip install Pillow to properly generate emoji PNGs
-
 ### On Debian or Ubuntu systems:
 
 #### Using the official Ubuntu repositories, PGroonga PPA and `tsearch-extras` deb package: