[Docs] Add tip of using dry-run flag; mention build dir setting.

docs/HowToGuides/GettingStarted.md

@@ -395,11 +395,12 @@ In project settings, locate `Build, Execution, Deployment > CMake`. You will nee
     - latest versions of the IDE suggest valid values here. Generally `RelWithDebInfoAssert` is a good one to work with
 - Toolchain: Default should be fine
 - Generator: Ninja
-- CMake options:
+- CMake options: You want to duplicate the essential CMake flags that `build-script` had used here, so CLion understands the build configuration. You can get the full list of CMake arguments from `build-script` by providing the `-n` dry-run flag; look for the last `cmake` command with a `-G Ninja`. Here is a minimal list of what you should provide to CLion here for this setting:
     - `-D SWIFT_PATH_TO_CMARK_BUILD=SOME_PATH/swift-project/build/Ninja-RelWithDebInfoAssert/cmark-macosx-arm64 -D LLVM_DIR=SOME_PATH/swift-project/build/Ninja-RelWithDebInfoAssert/llvm-macosx-arm64/lib/cmake/llvm -D Clang_DIR=SOME_PATH/swift-project/build/Ninja-RelWithDebInfoAssert/llvm-macosx-arm64/lib/cmake/clang -D CMAKE_BUILD_TYPE=RelWithDebInfoAssert -G Ninja -S .`
     - replace the `SOME_PATH` to the path where your `swift-project` directory is
     - the CMAKE_BUILD_TYPE should match the build configuration name, so if you named this profile `RelWithDebInfo` the CMAKE_BUILD_TYPE should also be `RelWithDebInfo`
     - **Note**: If you're using an Intel machine to build swift, you'll need to replace the architecture in the options. (ex: `arm64` with `x86_64`)
+- Build Directory: change this to the Swift build directory corresponding to the `build-script` run you did earlier, for example, `SOME_PATH/swift-project/build/Ninja-RelWithDebInfoAssert/swift-macosx-arm64`.
 
 With this done, CLion should be able to successfully import the project and have full autocomplete and code navigation powers.