fix typo CONTRIBUTING.md

Signed-off-by: iwantanode <[email protected]>

CONTRIBUTING.md

@@ -64,7 +64,7 @@ Leo is a big project, so (non-)adherence to best practices related to performanc
 ### Memory handling
 - If the final size is known, pre-allocate the collections (`Vec`, `HashMap` etc.) using `with_capacity` or `reserve` - this ensures that there are both fewer allocations (which involve system calls) and that the final allocated capacity is as close to the required size as possible.
 - Create the collections right before they are populated/used, as opposed to e.g. creating a few big ones at the beginning of a function and only using them later on; this reduces the amount of time they occupy memory.
-- If an intermediate vector is avoidable, use an `Iterator` instead; most of the time this just amounts to omitting the call to `.collect()` if a single-pass iteraton follows afterwards, or returning an `impl Iterator<Item = T>` from a function when the caller only needs to iterate over that result once.
+- If an intermediate vector is avoidable, use an `Iterator` instead; most of the time this just amounts to omitting the call to `.collect()` if a single-pass iteration follows afterwards, or returning an `impl Iterator<Item = T>` from a function when the caller only needs to iterate over that result once.
 - When possible, fill/resize collections "in bulk" instead of pushing a single element in a loop; this is usually (but not always) detected by `clippy`, suggesting to create vectors containing a repeated value with `vec![x; N]` or extending them with `.resize(N, x)`.
 - When a value is to eventually be consumed in a chain of function calls, pass it by value instead of by reference; this has the following benefits:
   * It makes the fact that the value is needed by value clear to the caller, who can then potentially reclaim it from the object afterwards if it is "heavy", limiting allocations.