Update branch of c-sdk repo to main (#223)

Also add missing apostrophe to stdint.readme

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
       - name: Checkout Parent Repo
         uses: actions/checkout@v2
         with:
-          ref: master
+          ref: main
           repository: aws/aws-iot-device-sdk-embedded-C
           path: main
       - name: Clone This Repo

include/stdint.readme

@@ -1,3 +1,28 @@
+/*
+ * FreeRTOS Kernel V10.4.2
+ * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * https://www.FreeRTOS.org
+ * https://github.com/FreeRTOS
+ *
+ */
 
 #ifndef FREERTOS_STDINT
 #define FREERTOS_STDINT
@@ -10,7 +35,7 @@
  * To use this file:
  *
  *    1) Copy this file into the directory that contains your FreeRTOSConfig.h
- *       header file, as that directory will already be in the compilers include
+ *       header file, as that directory will already be in the compiler's include
  *       path.
  *
  *    2) Rename the copied file stdint.h.