docs: sync chinese translation of build-system.rst
@@ -342,6 +342,7 @@ The following are some project/build variables that are available as build prope
- ``IDF_VERSION_MAJOR``, ``IDF_VERSION_MINOR``, ``IDF_VERSION_PATCH``: Components of ESP-IDF version, to be used in conditional expressions. Note that this information is less precise than that provided by ``IDF_VER`` variable. ``v4.0-dev-*``, ``v4.0-beta1``, ``v4.0-rc1`` and ``v4.0`` will all have the same values of ``IDF_VERSION_*`` variables, but different ``IDF_VER`` values.
- ``IDF_TARGET``: Name of the target for which the project is being built.
- ``PROJECT_VER``: Project version.
+
* If :ref:`CONFIG_APP_PROJECT_VER_FROM_CONFIG` option is set, the value of :ref:`CONFIG_APP_PROJECT_VER` will be used.
* Else, if ``PROJECT_VER`` variable is set in project CMakeLists.txt file, its value will be used.
* Else, if the ``PROJECT_DIR/version.txt`` exists, its contents will be used as ``PROJECT_VER``.
