Update readme

README.md

@@ -12,4 +12,46 @@ GitHub Mirror: https://github.com/sezero/quakespasm
 
 Releases: http://quakespasm.sourceforge.net/download.htm
 
-I'll try to keep the `upstream` branch up to date with the official repository.
+I'll try to keep the `upstream` branch up to date with the official repository.
+
+## Building & Running
+
+If you insist on building this version of QuakeSpasm, run the following:
+
+```
+git clone https://github.com/Diordany/quakespasm.git
+cd quakespasm/Quake
+make
+```
+
+Then run QuakeSpasm with:
+
+```
+./quakespasm
+```
+
+This version enables SDL2 by default. To use SDL-1.2, run:
+
+```
+make USE_SDL2=0
+```
+
+To include debug symbols, run:
+
+```
+make DEBUG=1
+```
+
+To enable user directory support, run:
+
+```
+make DO_USERDIRS=1
+```
+
+## Custom CVars
+
+Here's an overview of custom CVars that have been included in this version:
+
+| CVar               | Description                                                         |
+|:-------------------|:-------------------------------------------------------------------:|
+| ***con_printcmd*** | *Prints the names of commands that are being executed in realtime.* |