doc: build: fix typo in zephyr_cmake_package.rst

Corrected "This is means" to "This means"

Fixes #98714

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

Author: kartben

doc/build/zephyr_cmake_package.rst

@@ -18,7 +18,7 @@ When developing a Zephyr-based application, then a developer simply needs to wri
 ``find_package(Zephyr)`` in the beginning of the application :file:`CMakeLists.txt` file.
 
 To use the Zephyr CMake package it must first be exported to the `CMake user package registry`_.
-This is means creating a reference to the current Zephyr installation inside the
+This means creating a reference to the current Zephyr installation inside the
 CMake user package registry.