docs: per page descriptions (#328)

- add per-page descriptions for better cards in slack, etc
- regenerate changelog
- add keywords

Author: mnahkies

integration-tests/typescript-fetch/src/generate-release-notes.ts

@@ -49,6 +49,7 @@ async function main() {
   const notes = await generateReleaseNotes()
   const result = `---
 title: Release Notes
+description: Changelog of all OpenAPI Code Generator releases, including new features, bug fixes, breaking changes, and upgrade instructions for each version.
 ---
 
 import { Callout, Steps } from 'nextra/components'

packages/documentation/src/app/getting-started/quick-start/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: Quick Start
+description: A step-by-step guide to installing and using OpenAPI Code Generator with different client and server templates, including TypeSpec support.
 ---
 
 import {Steps, Tabs} from "nextra/components"

packages/documentation/src/app/getting-started/tips-for-writing-specifications/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: Tips for writing specifications
+description: Best practices and recommendations for writing high-quality OpenAPI specifications that generate better code and are easier to maintain.
 ---
 
 # Tips for writing a good specification
@@ -82,7 +83,7 @@ Produces something like:
 export type Apple = {}
 export type Pear = {}
 export type Fruit = Apple | Pear
-````
+```
 
 **Intersection Types**
 Using `allOf` of we can combine types / schemas into intersection types. This is often
@@ -107,7 +108,7 @@ Produces something like:
 ```typescript
 export type Profile = {}
 export type FullProfile = Profile & {}
-````
+```
 
 ## Use validation constraints where sensible
 

packages/documentation/src/app/guides/client-templates/typescript-angular/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: typescript-angular
+description: Generate a strongly-typed Angular client SDK based on the Angular HttpClient with RxJS Observable support for your OpenAPI or TypeSpec definitions.
 ---
 
 import {Callout, Tabs} from 'nextra/components'

packages/documentation/src/app/guides/client-templates/typescript-axios/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: typescript-axios
+description: Generate a strongly-typed axios client SDK with typed methods for each endpoint and optional runtime response validation for your OpenAPI or TypeSpec definitions.
 ---
 
 import {Callout, Tabs} from 'nextra/components'

packages/documentation/src/app/guides/client-templates/typescript-fetch/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: typescript-fetch
+description: Generate a strongly-typed fetch client SDK with typed methods, timeout support, and optional runtime response validation for your OpenAPI or TypeSpec definitions.
 ---
 
 import {Callout, Tabs} from 'nextra/components'

packages/documentation/src/app/guides/concepts/authenticated-input-specifications/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: Authenticated input specifications
+description: Learn how to access protected OpenAPI specifications by configuring authentication headers for remote URLs, with examples for Google Cloud IAP proxy and private GitHub repositories.
 ---
 
 # Authenticated input specifications
@@ -48,7 +49,7 @@ uri like `https://example.com` will send headers on any (`https`) request to tha
 such as `https://exmaple.com/some/path/openapi.yaml`
 
 ## Tips for generating the JSON
-Unfortunately it is a little annoying to formulate in shell scripts, so here's some examples to get you started.
+Unfortunately, it is a little annoying to formulate in shell scripts, so here's some examples to get you started.
 
 Typically, in any real use cases the secret values would be coming from other shell variables, eg: storing a
 short-lived access token, etc.

packages/documentation/src/app/guides/concepts/enums/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: Enums
+description: Understand how enumerated types are handled in code generation, including the difference between open and closed enums and how to ensure API compatibility when evolving your API.
 ---
 
 # Enumerated Types
@@ -59,6 +60,7 @@ enum:
 ```
 
 ### Server code (closed enum)
+
 For server templates, we just generate the exact `enum` values, meaning that an error will be raised both
 if a client sends us an unknown value, or the server attempts to respond with one.
 
@@ -122,6 +124,7 @@ This is interesting as it means that our server can start returning new enumerat
 updated to explicitly handle them, and it nudges developers to handle the unknown case gracefully.
 
 ## Customizing the behavior
+
 There are two ways you can customize this behavior
 
 - Global CLI option `--enum-extensibility <value>`
@@ -130,6 +133,7 @@ There are two ways you can customize this behavior
 Where `<value>` is either `open` or `closed`.
 
 Example:
+
 ```yaml
 type: string
 x-enum-extensibility: closed

packages/documentation/src/app/guides/concepts/extract-inline-schemas/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: Extract inline schemas
+description: Learn how to use the extract-inline-schemas feature to generate reusable types and schemas from inline OpenAPI definitions, reducing code duplication and improving maintainability.
 ---
 
 # Extract inline schemas

packages/documentation/src/app/guides/concepts/servers-object-handling/page.mdx

@@ -1,5 +1,6 @@
 ---
 title: Guide to servers object handling
+description: Understand how the OpenAPI servers object is processed in client SDK templates, including variable substitution, overrides, and typed base paths for flexible API endpoint configuration.
 ---
 
 import {Callout} from "nextra/components"
@@ -21,6 +22,7 @@ This is fully supported, including placeholder/variable substitution, and overri
 
 
 ## Overview
+
 Consider an example servers block:
 ```yaml
 servers: