clarify paths in readme

Author: lubynets

PWGHF/D2H/Macros/README.md

@@ -5,28 +5,31 @@ The fitter is **not** a part of O2Physics source code.
 
 ## Dependencies
 1. ROOT
-
 2. RapidJSON. Download the header-only (no compilation needed) RapidJSON library, see the link <https://rapidjson.org>.
 
+If you have O2Physics compilation you do not need to fulfill these dependencies explicitly.
+
 ## How to run
 ### As a ROOT macro
 The `runMassFitter.C` can be compiled as ROOT macro.
 ```
+cd path-to-o2physics-src/PWGHF/D2H/Macros
 source path-to-root-install/bin/thisroot.sh
 export ROOT_INCLUDE_PATH=$ROOT_INCLUDE_PATH:path-to-json-include
 root -l -x -b -q "HFInvMassFitter.cxx" "runMassFitter.C(\"config_massfitter.json\")"
 ```
-If you have O2Physics compilation and enter into its environment there is no need to set environment variables (skip first two lines above).
+If you have O2Physics compilation and enter into its environment there is no need to set environment variables (skip lines 2-3 above).
 
 ### As a CMake project
 It is also possible to compile the fitter as a CMake project or insert it into existing one if any.
 Use the `CMakeLists_HFInvMassFitter.txt` (rename it into `CMakeLists.txt` before usage).\
 Compile the fitter with the following steps:
 ```
+cd path-to-o2physics-src/PWGHF/D2H/Macros
 mkdir build
 cd build
 source path-to-root-install/bin/thisroot.sh
-cmake -DHFFITTER_RAPIDJSON_INCLUDE_DIRS=path-to-json-include ..
+cmake -DHFFITTER_RAPIDJSON_INCLUDE_DIRS=path-to-json-include ../
 make
 ```
 and run the fitter:
@@ -36,6 +39,7 @@ and run the fitter:
 ### Directly from the terminal
 Compile the fitter with the following steps:
 ```
+cd path-to-o2physics-src/PWGHF/D2H/Macros
 mkdir build
 cd build
 source path-to-root-install/bin/thisroot.sh