Add ARMv6 prebuild (#704)

Author: christianbundy

package.json

@@ -18,7 +18,7 @@
     "dependency-check": "dependency-check --no-dev -i napi-macros . test/*.js",
     "prepublishOnly": "npm run dependency-check",
     "prebuild-arm": "npm run prebuild-linux-arm && npm run prebuild-android-arm",
-    "prebuild-linux-arm": "prebuildify-cross -i linux-armv7 -i linux-arm64 -t 8.14.0 --napi --strip",
+    "prebuild-linux-arm": "prebuildify-cross -i linux-armv6 -i linux-armv7 -i linux-arm64 -t 8.14.0 --napi --strip",
     "prebuild-android-arm": "prebuildify-cross -i android-armv7 -i android-arm64 -t 8.14.0 --napi --strip",
     "prebuild-linux-x64": "prebuildify-cross -i centos7-devtoolset7 -i alpine -t 8.14.0 --napi --strip",
     "prebuild-darwin-x64": "prebuildify -t 8.14.0 --napi --strip"