[doc] Fix make invocations missed in #1070

Signed-off-by: Miguel Young de la Sota <mcyoung@google.com>
diff --git a/doc/ug/getting_started_fpga.md b/doc/ug/getting_started_fpga.md
index 2fc9a0b..17e6edf 100644
--- a/doc/ug/getting_started_fpga.md
+++ b/doc/ug/getting_started_fpga.md
@@ -115,9 +115,11 @@
 * Run the loading tool.
   ```console
   $ cd ${REPO_TOP}
-  $ make -C sw/device SW_DIR=examples/hello_world SW_BUILD_DIR=out clean all
-  $ make -C sw/host/spiflash clean all
-  $ ./sw/host/spiflash/spiflash --input=sw/device/out/sw.bin
+  $ ./meson_init.sh
+  $ ninja -C build-out/sw/fpga sw/device/examples/hello_world_export
+  $ ninja -C build-out/sw/fpga sw/host/spiflash/spiflash_export
+  $ build-bin/sw/host/spiflash/spiflash \
+      --input build-bin/sw/device/fpga/examples/hello_world/hello_world.bin
 
   Running SPI flash update.
   Image divided into 6 frames.