Fix typos

sky/sdk/README.md

diff --git a/sky/sdk/README.md b/sky/sdk/README.md
index 99df55c..b28384e 100644
--- a/sky/sdk/README.md
+++ b/sky/sdk/README.md
@@ -9,7 +9,7 @@
 
 1. *The Sky engine.* The engine is the core of the system. Written in C++, the
    engine provides the muscle of the Sky system. The engine provides
-   several primitives, including a soft real-time scheduler and a hierarchial,
+   several primitives, including a soft real-time scheduler and a hierarchical,
    retained-mode graphics system, that let you build high-quality apps.
 
 2. *The Sky framework.* The [framework](packages/sky/lib/framework) makes it
@@ -188,7 +188,7 @@
 system designed to provide cross-thread, cross-process, and language-agnostic
 communication between applications.  Sky uses Mojo IPC to make it possible
 to write UI code in Dart and yet depend on networking code, etc. written in
-another language.  Services are replacable, meaning that Dart code
+another language.  Services are replicable, meaning that Dart code
 written to use the `network_service` remains portable to any platform
 (iOS, Android, etc.) by simply providing a 'natively' written `network_service`.