[ci skip] Add pqr model

src/libs/models/pqr.js

+const mongoose = require('mongoose')
+
+const libs = `${process.cwd()}/libs`;
+const log = require(`${libs}/log`)(module);
+const User = require(`${libs}/models/user`);
+
+const Schema = mongoose.Schema;
+
+let PQRSchema = new Schema({
+    content: {
+        type: String,
+        required: true,
+    }
+});
+
+module.exports = mongoose.model('PQR', PQRSchema);