Moves swift package to root of repository so it can be used directly … (#7548)

* Moves swift package to root of repository so it can be used directly from the main repo

Fixing paths for swift directory

* Update swift readme

Package.swift

@@ -0,0 +1,37 @@
+// swift-tools-version:5.2
+/*
+ * Copyright 2020 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import PackageDescription
+
+let package = Package(
+  name: "FlatBuffers",
+  platforms: [
+    .iOS(.v11),
+    .macOS(.v10_14),
+  ],
+  products: [
+    .library(
+      name: "FlatBuffers",
+      targets: ["FlatBuffers"]),
+  ],
+  targets: [
+    .target(
+      name: "FlatBuffers",
+      dependencies: [],
+      path: "swift/Sources",
+      exclude: ["Documentation.docc/Resources/code/swift"]),
+  ])