add readme for C++

for-cpp/README.md

@@ -0,0 +1,57 @@
+*Applies to: Windows, MacOS, Linux*
+
+# Getting Started: C++
+
+1. Copy [Velopack.hpp](https://github.com/velopack/velopack.fusion/blob/master/for-cpp/Velopack.hpp) and [Velopack.cpp](https://github.com/velopack/velopack.fusion/blob/master/for-cpp/Velopack.cpp) into your project. 
+
+2. If you are on Linux or MacOS, you'll need [ICU4C](https://icu.unicode.org/) installed. Like many other C libraries, this is bundled into one package. 
+Installing the development package with your package manager (`apt` etc) is sufficient to make it available to compilers. The specific command you'll need is OS/Distro specific.
+
+3. Add the `Velopack::startup()` to your entry point (eg. `main()` or `wmain()`) as early as possible, ideally the first statement to run:
+```cpp
+#include "Velopack.hpp"
+
+wmain(int argc**, wchar_t *argv[ ], wchar_t *envp[ ])
+{
+    // velopack may exit / restart your app at this statement
+    Velopack::startup(argv, argc);
+
+    // ... your other startup code here
+}
+```
+
+3. Add auto-updates somewhere to your app:
+```cpp
+#include "Velopack.hpp"
+#include <memory>
+
+static void update_app()
+{
+    Velopack::UpdateManagerSync manager{};
+    manager.setUrlOrPath("https://the.place/you-host/updates");
+
+    std::shared_ptr<Velopack::UpdateInfo> updInfo = manager.checkForUpdates();
+    if (updInfo == nullptr) {
+        return; // no updates available
+    }
+
+    manager.downloadUpdates(updInfo->targetFullRelease.get());
+    manager.applyUpdatesAndRestart(updInfo->targetFullRelease.get());
+}
+```
+
+4. Compile your app to a program using your usual compiler (eg. msvc, cmake, gcc, etc)
+
+5. Install the `vpk` command line tool:
+```sh
+dotnet tool update -g vpk
+```
+***Note: you must have the .NET Core SDK 6 installed to use and update `vpk`***
+
+6. Package your Velopack release / installers:
+```sh
+vpk pack -u MyAppUniqueId -v 1.0.0 -p /myBuildDir -e myexename.exe
+```
+
+✅ You're Done! Your app now has auto-updates and an installer.
+You can upload your release to your website, or use the `vpk upload` command to publish it to the destination of your choice.