Add Makefile and tweak makefile

Makefile

@@ -4,7 +4,7 @@ BUILD_DIR = build/
 OBJ = $(patsubst %.c,$(BUILD_DIR)%.o,$(SRC_FILES))
 DEP = $(OBJ:.o=.d)
 
-RAYLIB_DIR = $(HOME)/Documents/Coding/raylib/build/
+RAYLIB_DIR ?= $(HOME)/Documents/Coding/raylib/build/
 LIB_DIRS = -L$(RAYLIB_DIR)lib
 INCLUDE_DIRS = -I$(RAYLIB_DIR)include -I.
 LIBS = -lraylib -lGL -lm -lpthread -ldl -lrt -lX11

README.md

@@ -0,0 +1,15 @@
+# FABRIK in C
+Implementation of 2D FABRIK in C. Drawing and input handling are done with [raylib](https://www.raylib.com/).
+
+## Build instruction
+1. Install raylib
+2. Set the RAYLIB\_DIR in the Makefile
+3. `make`
+
+## Usage
+- LMB to set the root position
+- `f` to toggle mouse following
+- `o` and `p` to decrease and increase the length respectively
+
+## Disclaimer
+This is a toy program. Probably won't get any more serious than this.