Add the installation and usage instructions.

README.md

@@ -1 +1,68 @@
-# StrEnum.System.Text.Json
+# StrEnum.System.Text.Json
+
+Allows for [StrEnum](https://github.com/StrEnum/StrEnum/) string enum JSON serialization and deserialization with System.Text.Json.
+
+The package targets .NET Standard 2.0 and can be used with System.Text.Json 4.6.0-6.\*.
+
+## Installation
+
+You can install [StrEnum.System.Text.Json](https://www.nuget.org/packages/StrEnum.System.Text.Json/) using the .NET CLI:
+
+```
+dotnet add package StrEnum.System.Text.Json
+```
+
+## Usage
+
+Create a string enum and a class that contains it:
+
+```csharp
+public class Sport : StringEnum<Sport>
+{
+    public static readonly Sport RoadCycling = Define("ROAD_CYCLING");
+}
+
+public class Race
+{
+    public string Name { get; set; }
+    public Sport Sport { get; set; }
+}
+```
+
+Configure `JsonSerializerOptions` by calling the `UseStringEnums()` method and pass it to `JsonSerializer` :
+
+```csharp
+var options = new JsonSerializerOptions().UseStringEnums();
+```
+
+### Serialize to JSON:
+
+```csharp
+var ctct = new Race { Name = "Cape Town Cycle Tour", Sport = Sport.RoadCycling };
+
+var json = JsonSerializer.Serialize(ctct, options);
+```
+
+The above produces:
+
+```json
+{"Name":"Cape Town Cycle Tour","Sport":"ROAD_CYCLING"}
+```
+
+### Deserialize from JSON:
+
+```csharp
+var race = JsonSerializer.Deserialize<Race>(json, options);
+```
+
+`race`  is equivalent to:
+
+```csharp
+new { Name = "Cape Town Cycle Tour", Sport = Sport.RoadCycling };
+```
+
+## License
+
+Copyright &copy; 2022 [Dmitry Khmara](https://dmitrykhmara.com).
+
+StrEnum is licensed under the [MIT license](LICENSE.txt).