Update README.md

add version of esp-idf

README.md

@@ -22,6 +22,9 @@ This project is built on the ESP32 IoT Development Framework (IDF) and utilizes
     <img src="https://img.shields.io/github/v/release/seeed-solution/SenseCAP_Indicator_ESP32?include_prereleases&color=blueviolet" alt="release">
   </a>
     <img src="https://img.shields.io/github/repo-size/seeed-solution/SenseCAP_indicator_ESP32" alt="repo-size">
+  <a href="https://docs.espressif.com/projects/esp-idf/en/release-v5.1/esp32/">
+    <img src="https://img.shields.io/badge/esp--idf-v5.1-00b202" alt="repo-size">
+  </a>
 </p>
 
 > Relevant: [SenseCAP Indicator RP2040](https://github.com/Seeed-Solution/SenseCAP_Indicator_RP2040) | [Share Your Projects HERE](https://github.com/Seeed-Solution/SenseCAP_Indicator_ESP32/discussions/33)