Clean up a few javadoc typos

core/src/main/java/hudson/EnvVars.java

@@ -65,7 +65,7 @@ public class EnvVars extends TreeMap<String,String> {
     /**
      * If this {@link EnvVars} object represents the whole environment variable set,
      * not just a partial list used for overriding later, then we need to know
-     * the platform for which this env vars are targeted for, or else we won't konw
+     * the platform for which this env vars are targeted for, or else we won't know
      * how to merge variables properly.
      *
      * <p>

core/src/main/java/hudson/os/SU.java

@@ -47,7 +47,7 @@ import java.util.Collections;
  * if necessary.
  *
  * <p>
- * A best effort is made to execute the closure as root, but we may still end up exeucting the closure
+ * A best effort is made to execute the closure as root, but we may still end up executing the closure
  * in the non-root privilege, so the closure should expect that and handle it gracefully.
  *
  * <p>