DONT MERGE

Author: threeal

README.md

@@ -46,6 +46,28 @@ add_executable(foo foo.cpp)
 target_link_libraries(foo PRIVATE errors::errors)
 ```
 
+## Usage
+
+This package contains an `errors::Error` class, representing an error object.
+A function that may result in errors should returns this object so that the error could be handled properly.
+
+```c++
+errors::Error print_hex(const char* number_str);
+
+int main() {
+  const auto err = print_hex(number_str);
+  if (err) {
+    // error, do something.
+  }
+
+  // no error, continue.
+}
+```
+
+On a function that returns `errors::Error`, it can returns `errors::nil` to indicate that there's no error or returns an error object
+
+See the [examples](./examples) for further details on how to use this package.
+
 ## License
 
 This project is licensed under the terms of the [MIT License](./LICENSE).