fix(docs): fixed support for old docs url, fixes #6960

docs/sources/installation/debian.md

@@ -3,6 +3,7 @@ title = "Installing on Debian / Ubuntu"
 description = "Install guide for Grafana"
 keywords = ["grafana", "installation", "documentation"]
 type = "docs"
+aliases = ["/installation/installation/"]
 [menu.docs]
 name = "Installing on Ubuntu / Debian"
 identifier = "debian"

docs/sources/installation/index.md

@@ -8,3 +8,14 @@ name = "Installation"
 identifier = "installation"
 +++
 
+## Installing Grafana
+
+- [Installing on Debian / Ubuntu](installation/debian)
+- [Installing on RPM-based Linux (CentOS, Fedora, OpenSuse, RedHat)](installation/rpm)
+- [Installing on Mac OS X](installation/mac)
+- [Installing on Windows](installation/windows)
+- [Installing on Docker](installation/docker)
+- [Installing using Provisioning (Chef, Puppet, Salt, Ansible, etc)](installation/provisioning)
+- [Nightly Builds](http://grafana.org/builds)
+
+