add m5stamp-c3 board

Author: jcgruenhage

boards/m5stamp-c3.json

@@ -0,0 +1,34 @@
+{
+  "build": {
+    "arduino":{
+      "ldscript": "esp32c3_out.ld"
+    },
+    "core": "esp32",
+    "f_cpu": "160000000L",
+    "f_flash": "40000000L",
+    "flash_mode": "qio",
+    "mcu": "esp32c3",
+    "variant": "esp32c3"
+  },
+  "connectivity": [
+    "wifi",
+    "bluetooth"
+  ],
+  "debug": {
+    "openocd_target": "esp32c3.cfg"
+  },
+  "frameworks": [
+    "arduino",
+    "espidf"
+  ],
+  "name": "M5Stamp C3",
+  "upload": {
+    "flash_size": "4MB",
+    "maximum_ram_size": 327680,
+    "maximum_size": 4194304,
+    "require_upload_port": true,
+    "speed": 460800
+  },
+  "url": "https://docs.m5stack.com/en/core/stamp_c3",
+  "vendor": "M5Stack"
+}