Add kitgen README

cmd/kitgen/README.md

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+# kitgen
+kitgen is an experimental code generation utility that helps with some of the
+boilerplate code required to implement the "onion" pattern `go-kit` utilizes.
+
+## Usage
+Before using this tool please explore the [testdata]() directory for examples
+of the inputs it requires and the outputs that will be produced. _You may not
+need this tool._ If you are new to and just learning `go-kit` or if your use
+case involves introducing `go-kit` to an existing codebase you are better
+suited by slowly building out the "onion" by hand.
+
+Before starting you need to *install* `kitgen` utility — see instructions below.
+1. **Define** your service. Create a `.go` file with the definition of your
+Service interface and any of the custom types it refers to:
+```go
+// service.go
+package profilesvc // don't forget to name your package
+
+type Service interface {
+    PostProfile(ctx context.Context, p Profile) error
+    // ...
+}
+type Profile struct {
+    ID        string    `json:"id"`
+    Name      string    `json:"name,omitempty"`
+    // ...
+}
+```
+2. **Generate** your code. Run the following command:
+```sh
+kitgen ./service.go
+# kitgen has a couple of flags that you may find useful
+
+# keep all code in the root directory
+kitgen -repo-layout flat ./service.go
+
+# put generated code elsewhere
+kitgen -target-dir ~/Projects/gohome/src/home.com/kitchenservice/brewcoffee
+```
+
+## Installation
+1. **Fetch** the `inlinefiles` utility. Go generate will use it to create your
+code:
+```
+go get github.com/nyarly/inlinefiles
+```
+2. **Install** the binary for easy access to `kitgen`. Run the following commands:
+```sh
+cd $GOPATH/src/github.com/go-kit/kit/cmd/kitgen
+go install
+
+# Check installation by running:
+kitgen -h
+```