[tcgc] license doc (#2394)

resolve: #2272

Author: tadelesh

website/src/content/current-sidebar.ts

@@ -74,6 +74,7 @@ const sidebar: SidebarItem[] = [
         "libraries/typespec-client-generator-core",
         "Azure.ClientGenerator.Core",
         false,
+        ["libraries/typespec-client-generator-core/guideline"],
       ),
       createLibraryReferenceStructure("libraries/azure-portal-core", "Azure.Portal", false),
     ],

website/src/content/docs/docs/howtos/Generate client libraries/13license.mdx

@@ -0,0 +1,73 @@
+---
+title: License
+---
+
+import { ClientTabs, ClientTabItem } from "@components/client-tabs";
+
+This page explains how the license info is generated in the client code.
+
+## Azure license
+
+For Azure scenarios, client code will always use the MIT license and include the license info in the header of the generated code or in a separate file depending on the language.
+
+For example, this is the license comment in the generated code of a Java client:
+
+```java
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+```
+
+This is the `LICENSE` file of a Python client library:
+
+```text
+Copyright (c) Microsoft Corporation
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the “Software”), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+```
+
+## Unbranded license
+
+For unbranded scenarios, client code will have no license info if there is no license configuration in `tspconfig.yaml`.
+Spec authors can set the license info with the `license` configuration in the `tspconfig.yaml`:
+
+```yaml
+license:
+  name: <License name. We have built-in "MIT License", "Apache License 2.0", "BSD 3-Clause License", "MPL 2.0", "GPL-3.0", and "LGPL-3.0". For other licenses, you need to set the link, header, and description manually.>
+  company: <Company name used in copyright>
+  link: <License link>
+  header: <License header in the generated code>
+  description: <License description in the separate license file>
+```
+
+For example, if you configure the license like the following, you will get the same license info as Azure scenarios:
+
+```yaml
+emit:
+  - "@azure-tools/typespec-python"
+  - "@azure-tools/typespec-java"
+options:
+  "@azure-tools/typespec-python":
+    license:
+      name: "MIT License"
+      company: "Microsoft Corporation"
+  "@azure-tools/typespec-java":
+    license:
+      name: "MIT License"
+      company: "Microsoft Corporation"
+```

website/src/content/docs/docs/libraries/typespec-client-generator-core/guideline.md

@@ -0,0 +1,55 @@
+---
+title: Guideline for client emitter
+---
+
+This document will guide you on how to use the TypeSpec Client Generator Core (TCGC) in client emitters.
+TCGC is a library that introduces a client type graph and provides useful helper functions for client emitters to generate client code.
+Client emitters do not need to interact with the TypeSpec core API directly; they can use the client type graph to obtain enough information to generate client code.
+
+## Basic concepts
+
+TODO
+
+## TCGC options
+
+TODO
+
+## Client type graph
+
+### Package
+
+[`SdkPackage`](../reference/js-api/interfaces/sdkpackage/) represents a client package. It contains all clients and types information in either a flattened structure or a namespace hierarchy. It also includes common information useful for client code generation.
+
+### License Info
+
+The `licenseInfo` property of the [`LicenseInfo`](../reference/js-api/interfaces/licenseinfo/) type in `SdkPackage` contains the license information to be used for client code license comments or license file generation.
+
+Client emitters should use `licenseInfo.name` (license name), `licenseInfo.link` (link to the official license document), `licenseInfo.header` (license sentences for code header comments), and `licenseInfo.description` (license sentences for separate license file) directly when generating license information in configuration files, code files, or license files. If `licenseInfo` is `undefined`, no license information should be included in the client code generation. Client emitters do not need to handle how the license information is configured.
+
+For Azure services, client emitters should hard-code the `license.name` configuration to `MIT License` when calling `createSdkContext`.
+
+```typescript
+export async function $onEmit(context: EmitContext<SdkEmitterOptions>) {
+  context.options.license = {
+    name: "MIT License",
+  };
+  const sdkContext = await createSdkContext(context);
+  // ...
+}
+```
+
+### Client
+
+TODO
+
+### Method
+
+TODO
+
+### Operation
+
+TODO
+
+### Type
+
+TODO