Update README to reflect cmake change

New CMakeLists.txt sets a default module search so -DCMAKE_MODULE_PATH is
no longer required in the command.

Change-Id: I95189ce2f36016b7c4929239d0e512851bec5ef6
Signed-off-by: Amber Lin <Amber.Lin@amd.com>


[ROCm/ROCR-Runtime commit: 7031a77428]

projects/rocr-runtime/README.md

@@ -17,7 +17,7 @@ A simple cmake-based system is available for building thunk. To build the thunk
 ```bash
     mkdir -p build
     cd build
-    cmake -DCMAKE_MODULE_PATH=${PWD}/../cmake_modules ..
+    cmake ..
     make
 ```
 
@@ -26,7 +26,7 @@ If the hsakmt-roct and hsakmt-roct-dev packages are desired:
 ```bash
     mkdir -p build
     cd build
-    cmake -DCMAKE_MODULE_PATH=${PWD}/../cmake_modules ..
+    cmake ..
     make package
     make package-dev
 ```