Sample text and API query working.

README.md

@@ -7,7 +7,8 @@ through PlatformIO and the Waveshare 4.2-inch V2 display. The display GPIO
 assignments are in `include/config.h`.
 
 1. Copy `src/secrets.h.example` to `src/secrets.h` and set your Wi-Fi SSID and
-   password. The actual `src/secrets.h` is ignored by Git.
+   password. The actual `src/secrets.h` is ignored by Git. It also contains
+   the public root certificate used to verify OpenF1's HTTPS connection.
 2. Build with `pio run -e pico_w`.
 3. Upload with `pio run -e pico_w -t upload`.
 4. Open the serial monitor with `pio device monitor -e pico_w`.