Update documentation

documentation/intrinsics.md

@@ -7,6 +7,16 @@ pre-existing binary-operators, but also some regular functions and associated
 functions (that every type has by-default). This document lists them all (except
 for the binary operators, because there are hundreds of those).
 
+### Global Intrinsics
+
+#### `malloc(size: u64) -> *u8`
+
+Allocates `size` bytes and returns a pointer of `u8` of length `size`.
+
+```rust
+i32::malloc(40); // Reserves 40 bytes
+```
+
 ### Associated Intrinsics
 
 #### `<T>::sizeof() -> u64`