adds usage examples

README.md

@@ -16,6 +16,56 @@ A kitchen sink of Go tools that I've found useful. Uses only the standard librar
 go get github.com/jritsema/gotoolbox
 ```
 
+### utils
+
+```go
+package main
+
+import utils "github.com/jritsema/gotoolbox"
+
+func main() {
+
+  s := []string{"a","b","c"}
+  if utils.SliceContains(&s, "b") {
+    fmt.Println("b exists")
+  }
+
+  err := utils.Retry(3, 1, func() error {
+    return callBrittleAPI()
+  })
+  if err != nil {
+    fmt.Println("callBrittleAPI failed after 3 retries: %w", err)
+  }
+
+  config, err := utils.ReadJSONFile("config.json")
+  if err != nil {
+    fmt.Println("error reading json file: %w", err)
+  }
+}
+```
+
+#### web framework
+
+```go
+package main
+
+import "github.com/jritsema/gotoolbox/web"
+
+type Data struct {
+  Hello string `json:"hello"`
+}
+
+func hello(r *http.Request) *web.Response {
+	return web.DataJSON(http.StatusOK, Data{Hello: "world"}, nil)
+}
+
+func main() {
+	mux := http.NewServeMux()
+	mux.Handle("/hello", web.Action(hello))
+	http.ListenAndServe(":8080", mux)
+}
+```
+
 ### development
 
 ```