Update readme

readme.md

@@ -2,5 +2,138 @@
 A .NET library for interacting with the [Gravatar](https://gravatar.com/) API.
 
 
+## Installation
+Install the library via [NuGet](https://www.nuget.org/packages/gravatar-dotnet):
+```bash
+dotnet add package gravatar-dotnet
+```
+
+### Extensions
+Install optional library extensions for more functionality, depending on your use case.
+#### Dependency Injection
+Integrate gravatar-dotnet and your DI container of choice. Install the extension library via [NuGet](https://www.nuget.org/packages/gravatar-dotnet-dependencyinjection):
+```bash
+dotnet add package gravatar-dotnet-dependencyinjection
+```
+#### ASP.Net Core Additions
+Integrate gravatar-dotnet and ASP.NET Core with Razor Tag Helpers for avatars and profile QR codes. Install the extension library via [NuGet](https://www.nuget.org/packages/gravatar-dotnet-aspnetcore):
+```bash
+dotnet add package gravatar-dotnet-aspnetcore
+```
+
+
+## Usage
+1. Obtain an API key from the [Gravatar Developer Dashboard](https://gravatar.com/developers/applications) (requires a Gravatar account and developer application).
+2. Pass the API key into a new instance of the `GravatarService` class or use a configured `HttpClient` if advanced configuration (e.g., proxies) is required.
+3. Use the methods available on `GravatarService` to interact with the Kagi API.
+
+### Initialization
+The library can be initialized in three ways:
+#### Basic Initialization
+Pass in your API key directly:
+```csharp
+var gravatar = new GravatarService("YOUR_GRAVATAR_API_KEY");
+```
+#### Advanced Initialization
+Use an existing `HttpClient`, ensuring that `BaseAddress` and an `Authorization` header have been set:
+```csharp
+var httpClient = new HttpClient
+{
+    BaseAddress = new Uri("https://api.gravatar.com/v3/"),
+    Timeout = TimeSpan.FromSeconds(5)
+};
+
+httpClient.DefaultRequestHeaders.Authorization =
+	new AuthenticationHeaderValue("Bearer", "YOUR_GRAVATAR_API_KEY");
+
+var gravatar = new GravatarService(httpClient);
+```
+#### Dependency Injection
+If you've installed the appropriate extension library.
+1. Register `GravatarService` with your dependency container:
+```csharp
+services.AddGravatarHttpClient(options =>
+{
+	options.BaseUrl = new Uri("https://kagi.com/api/v0/");
+	options.ApiKey = "YOUR_KAGI_API_KEY";
+});
+```
+2. Inject `IGravatarService` where needed:
+```csharp
+public class MyClass
+{
+    private readonly IGravatarService gravatar;
+
+    public MyClass(IGravatarService gravatar)
+    {
+        this.gravatar = gravatar;
+    }
+}
+```
+
+### Getting an Avatar URL
+You can construct a valid Gravatar Avatar URL as follows:
+```csharp
+var gravatarAvatarUrl =
+	GravatarHelper.GetAvatarUrl(
+		"[email protected]",
+		size: 64,
+		defaultValue: GravatarAvatarDefault.Identicon,
+		forceDefaultValue: false,
+		rating: GravatarAvatarRating.G,
+		withFileExtension: false)
+```
+To retrieve the avatar image, make a HTTP GET request to the URL that is returned.
+
+### Getting a Profile
+```csharp
+var gravatarProfile =
+    await gravatar.GetProfileAsync(
+        GravatarHelper.GetEmailAddressHash(
+            "[email protected]"));
+```
+
+### Getting a Profile QR Code URL
+You can construct a valid Gravatar Profile QR Code URL as follows:
+```csharp
+var gravatarProfileQRCodeUrl =
+	GravatarHelper.GetProfileQRCodeUrl(
+		"[email protected]",
+		size: 256,
+		type: GravatarProfileQRCodeType.Logo,
+		version: GravatarProfileQRCodeVersion.Modern)
+```
+To retrieve the profile QR code image, make a HTTP GET request to the URL that is returned.
+
+### Using Tag Helpers
+If you've installed the appropriate extension library, add the following to your `_ViewImport.cshtml`:
+```razor
+@addTagHelper *, Gravatar.Extensions.AspNetCore
+```
+
+To automatically construct the `src` URL for an `img` tag from a Gravatar Avatar URL, use `gravatar-avatar` and the various `gravatar-*` attributes supplied.
+```razor
+<img gravatar-avatar
+     gravatar-email-address="Context.User.Claims..."
+     gravatar-default="identicon"
+     ... />
+```
+
+To automatically construct the `src` URL for an `img` tag from a Gravatar Profile QR Code URL, use `gravatar-profile-qrcode` and the various `gravatar-*` attributes supplied.
+```razor
+<img gravatar-profile-qrcode
+     gravatar-email-address="Context.User.Claims..."
+     ... />
+```
+
+
+## Documentation
+Refer to the [Usage](#usage) section above for a quick start, or consult the inline documentation while working in your IDE. For detailed information about the underlying API endpoints, parameters, and expected responses, refer to the [official Gravatar API documentation](https://docs.gravatar.com/api/profiles/rest-api/).
+
+
+## Contributing
+Contributions are welcome! To contribute, fork the repository, create a new branch, and submit a pull request with your changes. Please make sure all tests pass before submitting.
+
+
 ## License
 This project is licensed under the MIT license. See `license.txt` for full details.