improve documentation

Change-Id: I5561d4f64632235340faa619d490266f991c7f1e

Author: rdementi

README.md

@@ -74,7 +74,7 @@ or clone the repository first, and then update submodules with:
 git submodule update --init --recursive
 ```
 
-Install cmake then:
+Install cmake (and libasan on Linux) then:
 
 ```
 mkdir build

src/CMakeLists.txt

@@ -84,7 +84,7 @@ if(UNIX)  # LINUX, FREE_BSD, APPLE
             set(PCM_DYNAMIC_ASAN "")
             set(PCM_STATIC_ASAN "-static-libasan")
             message(STATUS "Using static libasan")
-            message(STATUS "To use dynamic libasan, use -DPCM_NO_STATIC_LIBASAN=1 option (required for CentOS)")
+            message(STATUS "To use dynamic libasan, use -DPCM_NO_STATIC_LIBASAN=1 option (required for CentOS and arch Linux)")
         endif()
     endif()