fix(docs): fix the indent and the build command for MT8188

This patch includes
- Fix the indent.
- LD argument is no longer needed. Remove LD parameter from the build
  command.

Change-Id: I615704cf6f4b6fd9e37c047b18c40f00652e269d
Signed-off-by: Yidi Lin <yidilin@chromium.org>
diff --git a/docs/plat/mt8188.rst b/docs/plat/mt8188.rst
index 93abaa5..57b93ac 100644
--- a/docs/plat/mt8188.rst
+++ b/docs/plat/mt8188.rst
@@ -13,9 +13,9 @@
 
     Boot Rom --> Coreboot --> TF-A BL31 --> Depthcharge --> Linux Kernel
 
-    How to Build
-    ------------
+How to Build
+------------
 
-    .. code:: shell
+.. code:: shell
 
-           make CROSS_COMPILE=aarch64-linux-gnu- LD=aarch64-linux-gnu-gcc PLAT=mt8188 DEBUG=1 COREBOOT=1
+    make CROSS_COMPILE=aarch64-linux-gnu- PLAT=mt8188 DEBUG=1 COREBOOT=1