Maintenance -- clean up readme.txt and add url to GitHub. (FreeRTOS#38)

* Removing readme.txt, as now we have README.md in place.

The only information missing from README.md is about FAQ.

* Adding FAQ information in README.md.

* Adding a .url to root to redict user to FreeRTOS github home page.

Author: yuhui-zheng

GitHub-FreeRTOS-Home.url

@@ -0,0 +1,8 @@
+[{000214A0-0000-0000-C000-000000000046}]
+Prop3=19,2
+[InternetShortcut]
+URL=https://github.com/FreeRTOS/FreeRTOS
+IconIndex=0
+IDList=
+HotKey=0
+

README.md

@@ -4,7 +4,7 @@ The easiest way to use FreeRTOS is to start with one of the pre-configured demo
 Additionally, for FreeRTOS kernel feature information refer to the [Developer Documentation](https://www.freertos.org/features.html), and [API Reference](https://www.freertos.org/a00106.html).
 
 ### Getting help
-If you have any questions or need assistance troubleshooting your FreeRTOS project, we have an active community that can help on the [FreeRTOS Community Support Forum](https://forums.freertos.org).
+If you have any questions or need assistance troubleshooting your FreeRTOS project, we have an active community that can help on the [FreeRTOS Community Support Forum](https://forums.freertos.org). Please also refer to [FAQ](http://www.freertos.org/FAQHelp.html) for frequently asked questions.
 
 ## Cloning this repository
 This repo uses [Git Submodules](https://git-scm.com/book/en/v2/Git-Tools-Submodules) to bring in dependent components.