typo fix

Author: Conaclos

src/tlsf.rs

@@ -155,8 +155,8 @@ unsafe impl GlobalAlloc for Heap {
     }
 
     unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
-        // SAFETY: `layout.align()` is a power of two, and the size preconidtion
-        // is upheld by the caller
+        // SAFETY: `layout.align()` is a power of two,
+        // and the size precondition is upheld by the caller.
         let new_layout =
             unsafe { core::alloc::Layout::from_size_align_unchecked(new_size, layout.align()) };
         self.realloc(ptr, new_layout)