readme update 2

Author: xtruan

README.md

@@ -6,15 +6,16 @@ Crypto toolkit for Flipper Zero
 The goal of this project is to see how much crypto functionality can be brought to the Flipper Zero.
 
 ## How to install on Flipper Zero
-- If you do not have one, download a Flipper Zero firmware to get the `fbt` build tool.
-- Plug your Flipper Zero in via USB.
-- Copy the contents of this folder into the applications_user folder of your firmware.
+- If you do not have one, download a Flipper Zero firmware to get the `fbt` build tool
+- Plug your Flipper Zero in via USB
+- Copy the contents of this folder into the applications_user folder of your firmware
+- Modify the `site_scons/cc.scons` file in the Flipper Zero firmware to remove the `"-Wdouble-promotion"` warning and add the `"-Os"` flag
 
 Then run the command: 
  ```
 .\fbt COMPACT=1 DEBUG=0 launch_app APPSRC=applications_user/FlipBIP
  ```
-The application will be compiled and copied onto your device.
+The application will be compiled and copied onto your device
 
 ## Status