Merge pull request #3142 from mbrobbel/typo

Fix typos in 1398 and 2451

Author: kennytm

text/1398-kinds-of-allocators.md

@@ -741,7 +741,7 @@ methods; so `a.alloc_unchecked(layout)` will return an `Option<Address>`
 (where `None` corresponds to allocation failure).
 
 The idea here is that `Allocator` implementors are encouraged
-to streamline the implmentations of such methods by assuming that all
+to streamline the implementations of such methods by assuming that all
 of the preconditions hold.
 
  * However, to ease initial `impl Allocator` development for a given

text/2451-re-rebalancing-coherence.md

@@ -153,7 +153,7 @@ following:
 > type parameter.
 >
 > Rust requires that for any given trait and any given type, there is at most one
-> implmentation of that trait. An important piece of this is that we disallow
+> implementation of that trait. An important piece of this is that we disallow
 > implementing a trait from another crate for a type parameter.
 >
 > Rust's orphan rule always permits an impl if either the trait or the type being