Minor typo/spelling fixes (#1505)

Author: Cito

src/subscription/subscribe.js

@@ -42,7 +42,7 @@ import { getOperationRootType } from '../utilities/getOperationRootType';
  * compliant subscription, a GraphQL Response (ExecutionResult) with
  * descriptive errors and no data will be returned.
  *
- * If the the source stream could not be created due to faulty subscription
+ * If the source stream could not be created due to faulty subscription
  * resolver logic or underlying systems, the promise will resolve to a single
  * ExecutionResult containing `errors` and no `data`.
  *

src/validation/__tests__/KnownArgumentNames-test.js

@@ -268,7 +268,7 @@ describe('Validate: Known argument names', () => {
       ]);
     });
 
-    it('unknown arg on overrided standard directive', () => {
+    it('unknown arg on overridden standard directive', () => {
       expectSDLErrors(`
         type Query {
           foo: String @deprecated(reason: "")

src/validation/__tests__/KnownDirectives-test.js

@@ -207,7 +207,7 @@ describe('Validate: Known directives', () => {
       `).to.deep.equal([]);
     });
 
-    it('with overrided standard directive', () => {
+    it('with overridden standard directive', () => {
       expectSDLErrors(`
         schema @deprecated {
           query: Query

src/validation/__tests__/ProvidedRequiredArguments-test.js

@@ -321,7 +321,7 @@ describe('Validate: Provided required arguments', () => {
       ]);
     });
 
-    it('Missing arg on overrided standard directive', () => {
+    it('Missing arg on overridden standard directive', () => {
       expectSDLErrors(`
         type Query {
           foo: String @deprecated