[docs] Update commands in zircon vim2 docs

Updated commands to reflect changes in the build tools.

Ran the new commands to make sure the work as expected.

Change-Id: Ic18eb7ec23e1ab9561934401c6003a257fde49ba
diff --git a/zircon/docs/targets/khadas-vim.md b/zircon/docs/targets/khadas-vim.md
index afdc587..dc84412 100644
--- a/zircon/docs/targets/khadas-vim.md
+++ b/zircon/docs/targets/khadas-vim.md
@@ -57,9 +57,10 @@
 
 ## Building Zircon
 
+You'll need to build with ```-t``` to disable tests so that the image will fit in the boot partition.
+
 ```
-gn gen build-zircon
-ninja -C build-zircon
+scripts/build-zircon-arm64 -t
 ```
 
 Be sure you've already set up your network before proceeding to the next step.
@@ -95,13 +96,13 @@
 To netboot zircon, enter zedboot and run the following under the zircon directory:
 
 ```
-scripts/netboot-zircon ./build-arm64
+scripts/netboot-zircon-arm64 ./build-gcc
 ```
 
 To netboot garnet, run the following under the fuchsia directory:
 
 ```
-fx set arm64 --board vim2 --netboot && fx full-build && fx netboot -1
+fx set core.vim2 --netboot && fx build && fx netboot -1
 ```
 
 You should be able to see "Issued boot command to ..." message printed out if this step is successful.
@@ -111,7 +112,7 @@
 Paving is available from garnet layers and above. Run the following under the fuchsia directory:
 
 ```
-fx set arm64 --release --board vim2 && fx full-build && fx pave -1
+fx set core.vim2 --release && fx build && fx pave -1
 ```
 
 ### Fuchsia logo