Add keywords field to platform manifest

Author: valeros

platform.json

@@ -4,6 +4,13 @@
   "description": "The NXP LPC is a family of 32-bit microcontroller integrated circuits by NXP Semiconductors. The LPC chips are grouped into related series that are based around the same 32-bit ARM processor core, such as the Cortex-M4F, Cortex-M3, Cortex-M0+, or Cortex-M0. Internally, each microcontroller consists of the processor core, static RAM memory, flash memory, debugging interface, and various peripherals.",
   "homepage": "http://www.nxp.com/products/microcontrollers/",
   "license": "Apache-2.0",
+  "keywords": [
+      "dev-platform",
+      "ARM",
+      "Cortex-M",
+      "NXP Semiconductors",
+      "LPC"
+  ],
   "engines": {
     "platformio": "<5"
   },