Doc: Fix build command for profiling

Signed-off-by: Jianliang Shen <jianliang.shen@arm.com>
Change-Id: I588758f59249dc83c54b5796e8b53b89e49ac361
diff --git a/docs/profiling.rst b/docs/profiling.rst
index 18fdf7d..e9d9247 100644
--- a/docs/profiling.rst
+++ b/docs/profiling.rst
@@ -42,7 +42,7 @@
   cmake --build build/spe -- install -j
 
   # Build NSPE
-  cmake -S . -B build/nspe -DCONFIG_SPE_PATH=build/spe/api_ns \
+  cmake -S . -B build/nspe -DCONFIG_SPE_PATH=${PWD}/build/spe/api_ns \
         -DTFM_TOOLCHAIN_FILE=build/spe/api_ns/cmake/toolchain_ns_GNUARM.cmake
   cmake --build build/nspe -- -j