Add prerequisite

diff --git a/Documentation/BUILDING.md b/Documentation/BUILDING.md
index 93c4da4c944f124b1c9c5a5b4bc520eae61c24ec..92fd9eac1308e5e1a0ba260c0ff871ab643184ad 100644 (file)
--- a/Documentation/BUILDING.md
+++ b/Documentation/BUILDING.md
@@ -1,6 +1,6 @@
 # Building
 ## Prerequisites
-The build system of this repository is based on Make. The `Makefile` is in the base of the repository.
+The build system of this repository is based on Make. The `Makefile` is in the base of the repository. Please ensure you have `arduino-cli` installed before proceeding.
 
 Firstly, figure out which MCU platform your supported board is based on. The table below can help you.