add readme for each package

README.md

@@ -0,0 +1,35 @@
+# Go Validate
+
+A suite of straightforward validation functions. You put something in, you get back `nil` or an error.
+
+## Error handling
+
+You can use `errors.Is()` to ascertain the type of errors thrown by validation functions. This may be helpful to control side effects, particularly if using multiple validators and returning early (similar to a strongly-typed try-catch). For example:
+
+## Example
+
+```go
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/annybs/go/validate"
+)
+
+func main() {
+	v := validate.Equal("a")
+	if err := v("b"); err != nil {
+		if errors.Is(err, validate.ErrNotEqual) {
+			fmt.Println("failed successfully")
+		} else {
+			fmt.Println("failed unsuccessfully")
+		}
+	}
+}
+```
+
+## License
+
+See [LICENSE.md](../LICENSE.md)