replace CONTROL by json

vcpkg/etcd-cpp-apiv3/CONTROL

@@ -1,6 +0,0 @@
-Source: etcd-cpp-apiv3
-Version: 0.2.8
-Homepage: https://github.com/etcd-cpp-apiv3/etcd-cpp-apiv3
-Description: The etcd-cpp-apiv3 is a C++ API for etcd's v3 client API, i.e., ETCDCTL_API=3.
-Build-Depends: boost-asio, boost-system, boost-thread, boost-random,
-               cpprestsdk, grpc, openssl, protobuf

vcpkg/etcd-cpp-apiv3/vcpkg.json

@@ -0,0 +1,16 @@
+{
+  "name": "etcd-cpp-apiv3",
+  "version-string": "0.2.8",
+  "description": "The etcd-cpp-apiv3 is a C++ API for etcd's v3 client API, i.e., ETCDCTL_API=3.",
+  "homepage": "https://github.com/etcd-cpp-apiv3/etcd-cpp-apiv3",
+  "dependencies": [
+    "boost-asio",
+    "boost-random",
+    "boost-system",
+    "boost-thread",
+    "cpprestsdk",
+    "grpc",
+    "openssl",
+    "protobuf"
+  ]
+}