Add links to video tutorials.

README.md

@@ -4,6 +4,7 @@ TrenchBroom is a modern cross-platform level editor for Quake-engine based games
 
 - Website:   http://kristianduske.com/trenchbroom
 - Discord:   https://discord.gg/n7K8Cps
+- Tutorial:  https://www.youtube.com/watch?v=gONePWocbqA
 
 [![Build Status](https://travis-ci.org/kduske/TrenchBroom.svg?branch=release%2Fv2.0.0)](https://travis-ci.org/kduske/TrenchBroom) [![Build status](https://ci.appveyor.com/api/projects/status/github/kduske/trenchbroom?branch=release%2Fv2.0.0&svg=true)](https://ci.appveyor.com/project/kduske/trenchbroom/branch/release/v2.0.0)
 

app/resources/documentation/manual/index.md

@@ -1845,6 +1845,7 @@ Open the "About TrenchBroom" dialog from the menu. The light gray text on the le
 
 - [TrenchBroom on github] - TrenchBroom's github page
 - [func_msgboard] - Quake Mapping Forum
+- [Tutorials by dumptruck_ds] - Video Tutorial Series
 - [Tome of Preach] - Quake Map Hacks and QuakeC Hacks
 
 [TrenchBroom on github]: http://github.com/kduske/TrenchBroom/
@@ -1853,3 +1854,4 @@ Open the "About TrenchBroom" dialog from the menu. The light gray text on the le
 [Tome of Preach]: https://tomeofpreach.wordpress.com/
 [FGD File Format]: http://developer.valvesoftware.com/wiki/FGD
 [Discord]: https://discord.gg/n7K8Cps
+[Tutorials by dumptruck_ds]: https://www.youtube.com/watch?v=gONePWocbqA