various docs updates

docs/reference/math.md

@@ -0,0 +1,37 @@
+# Math
+
+[Numeric](/reference/types/number) values: 0, 1, 2, ...
+
+```blocks
+0;
+1;
+2;
+```
+
+Arithmetic binary operation (+, -, *, /)
+
+```blocks
+0+1;
+0-1;
+1*2;
+3/4;
+```
+
+Absolute value
+
+```blocks
+Math.abs(-5);
+```
+
+Minimum/maximum of two values
+
+```blocks
+Math.min(0, 1);
+Math.max(0, 1);
+```
+
+Random value
+
+```blocks
+Math.random(5);
+```