update doc

docs/lib2x-lsystem3.md

@@ -2,17 +2,17 @@
 
 `lsystem3` is a 3D implementation of [L-system](https://en.wikipedia.org/wiki/L-system). It's based on the algorithm of turtle grahpics. Instructions for generation of rules are as follows:
 
-   F  Move forward and draw line
-   f  Move forward without drawing a line
-   +  Turn left
-   -  Turn right
-   |  Reverse direction (ie: turn by 180 degrees)
-   &  Pitch down
-   ^  Pitch up
-   \  Roll left
-   /  Roll right       
-   [  Push current turtle state onto stack
-   ]  Pop current turtle state from the stack
+	F  Move forward and draw line
+	f  Move forward without drawing a line
+	+  Turn left
+	-  Turn right
+	|  Reverse direction (ie: turn by 180 degrees)
+	&  Pitch down
+	^  Pitch up
+	\  Roll left
+	/  Roll right       
+	[  Push current turtle state onto stack
+	]  Pop current turtle state from the stack
 
 **Since:** 2.4