Update README.md to remove dead link.

See the conversation 42c627b2b8 (comments) .

Linkage for both ```./FreeRTOS/Source``` and ```./FreeRTOS/Demo``` are removed, since it looks weird to only provide linkage to Demo.

README.md

@@ -31,9 +31,9 @@ This repository contains the FreeRTOS Kernel, a number of supplementary librarie
 ### Kernel sources
 The FreeRTOS Kernel Source is in [FreeRTOS/FreeRTOS-Kernel repository](https://github.com/FreeRTOS/FreeRTOS-Kernel), and it is consumed as a submodule in this repository.
 
-The version of the FreeRTOS Kernel Source in use could be accessed at [```./FreeRTOS/Source```](https://github.com/FreeRTOS/FreeRTOS/tree/master/FreeRTOS/Source)
+The version of the FreeRTOS Kernel Source in use could be accessed at ```./FreeRTOS/Source``` directory.
 
-A number of Demo projects can be found under [```./FreeRTOS/Demo```](https://github.com/FreeRTOS/FreeRTOS/tree/master/FreeRTOS/Demo)
+A number of Demo projects can be found under ```./FreeRTOS/Demo``` directory.
 
 ### Supplementary library sources
 The [FreeRTOS-Plus/Source](https://github.com/FreeRTOS/FreeRTOS/tree/master/FreeRTOS-Plus/Source) directory contains source code for some of the FreeRTOS+ components, as well as select partner provided libraries. These subdirectories contain further readme files and links to documentation.