Removed Debian/RHEL references from installation docs

docs/installation/netbox.md

@@ -1,6 +1,6 @@
 # Installation
 
-**Debian/Ubuntu**
+**Ubuntu**
 
 Python 3:
 
@@ -15,7 +15,7 @@ Python 2:
 # apt-get install -y python2.7 python-dev python-pip libxml2-dev libxslt1-dev libffi-dev graphviz libpq-dev libssl-dev zlib1g-dev
 ```
 
-**CentOS/RHEL**
+**CentOS**
 
 Python 3:
 
@@ -57,13 +57,13 @@ Create the base directory for the NetBox installation. For this guide, we'll use
 
 If `git` is not already installed, install it:
 
-**Debian/Ubuntu**
+**Ubuntu**
 
 ```no-highlight
 # apt-get install -y git
 ```
 
-**CentOS/RHEL**
+**CentOS**
 
 ```no-highlight
 # yum install -y git

docs/installation/postgresql.md

@@ -1,15 +1,18 @@
 NetBox requires a PostgreSQL database to store data. (Please note that MySQL is not supported, as NetBox leverages PostgreSQL's built-in [network address types](https://www.postgresql.org/docs/9.1/static/datatype-net-types.html).)
 
+!!! note
+    The installation instructions provided here have been tested to work on Ubuntu 16.04 and CentOS 6.9. The particular commands needed to install dependencies on other distributions may vary significantly. Unfortunately, this is outside the control of the NetBox maintainers. Please consult your distribution's documentation for assistance with any errors.
+
 # Installation
 
-**Debian/Ubuntu**
+**Ubuntu**
 
 ```no-highlight
 # apt-get update
 # apt-get install -y postgresql libpq-dev
 ```
 
-**CentOS/RHEL**
+**CentOS**
 
 ```no-highlight
 # yum install -y postgresql postgresql-server postgresql-devel

docs/installation/web-server.md

@@ -3,7 +3,7 @@
 We'll set up a simple WSGI front end using [gunicorn](http://gunicorn.org/) for the purposes of this guide. For web servers, we provide example configurations for both [nginx](https://www.nginx.com/resources/wiki/) and [Apache](http://httpd.apache.org/docs/2.4). (You are of course free to use whichever combination of HTTP and WSGI services you'd like.) We'll also use [supervisord](http://supervisord.org/) to enable service persistence.
 
 !!! info
-    Only Debian/Ubuntu instructions are provided here, but the installation process for CentOS/RHEL does not differ much. Please consult the documentation for those distributions for details.
+    For the sake of brevity, only Ubuntu 16.04 instructions are provided here, but this sort of web server and WSGI configuration is not unique to NetBox. Please consult your distribution's documentation for assistance if needed.
 
 ```no-highlight
 # apt-get install -y gunicorn supervisor