Tweaked README.md on how to used the --mode=config xmake option

1 files changed, 7 insertions, 5 deletions

diff --git a/README.md b/README.md
index 77dddfb80..0981e8af8 100644
--- a/README.md
+++ b/README.md
@@ -101,15 +101,17 @@ Clone the Zen project and tell `xmake` to use the correct GCC version;
 ```
 git clone https://github.com/EpicGames/zen.git ~/zen/main
 cd ~/zen/main
-xmake config --plat=linux --cxx=g++-11 --cc=gcc-11
+xmake config --plat=linux --cxx=g++-11 --cc=gcc-11 [--mode=debug]
 ```
 
-Now we are ready to build Zen. The `--mode=debug` is optional. It has been
-included below to show how to change build variants. The `-y` skips `xmake` from
-prompting about updating `vcpkg` packages;
+The `--mode=debug` is optionally required to change the build variant. This
+cannot be done when executing the build and the setting of configuration options
+can not be composed across multiple `xmake config` calls.
+
+Now we are ready to build Zen.  The `-y` skips `xmake` from prompting about
+updating `vcpkg` packages;
 
 ```
-xmake config --mode=debug
 xmake build -y
 ```