docs(Capitalize): Add Capitalize documentation

docs/ko/reference/built-in/Capitalize.md

@@ -1 +1,70 @@
-# Capitalize
+# Capitalize\<StringType>
+
+:::info
+`Capitalize\<StringType>`은 TypeScript 2.8 이상에서 사용할 수 있는 내장 유틸리티 타입이에요. 자세한 내용은 [타입스크립트 핸드북](https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html#uppercasestringtype)과 [릴리즈 노트](https://devblogs.microsoft.com/typescript/announcing-typescript-4-1/)를 참고해주세요.
+:::
+
+## 개요
+
+`Capitalize<StringType>` 유틸리티 타입은 문자열 리터럴 타입의 첫 글자를 대문자로 표시하고 나머지 문자는 변경하지 않아요.
+
+## 구문
+
+```ts
+type Capitalize<S extends string> = S extends `${infer F}${infer Rest}` ? `${UpperCase<F>}${Rest}` : S;
+```
+
+- **StringType (S)**: 첫 글자를 대문자로 바꿀 문자열이에요.
+
+## 예제
+
+#### 예제 #1
+
+```ts
+type LowercaseGreeting = 'hello, world';
+type Greeting = Capitalize<LowercaseGreeting>; // 'Hello, world'
+```
+
+#### 예제 #2
+
+```ts
+type FormEventNames = 'submit' | 'reset' | 'change' | 'input' | 'focus' | 'blur' | 'invalid';
+type CapitalizedFormEventNames = Capitalize<FormEventNames>; // 'Submit' | 'Reset' | 'Change' | 'Input' | 'Focus' | 'Blur' | 'Invalid'
+type FormHandlerNames = `on${CapitalizedFormEventNames}`; // 'onSubmit' | 'onReset' | 'onChange' | 'onInput' | 'onFocus' | 'onBlur' | 'onInvalid'
+type FormHandlers = {
+  [FormHandlerName in FormHandlerNames]: (event: Event) => void;
+};
+```
+
+#### 예제 #3
+
+```ts
+interface UserStoreState {
+  id: number;
+  name: string;
+  age: number;
+}
+
+// 프로퍼티명을 setter 함수명으로 변환하는 타입이에요.
+// 예를 들어, 'name'이 주어졌을 때, `setName`으로 변환해요.
+type ConvertToSetter<S extends string> = `set${Capitalize<S>}`;
+
+// 상태를 기반로 setter 함수 타입을 생성해요.
+// StoreState의 각 프로퍼티에 대해 setter 함수 타입을 생성해요.
+type StoreSetters<StoreState> = {
+  [K in keyof StoreState as ConvertToSetter<string & K>]: (value: StoreState[K]) => void;
+};
+
+// 상태와 setter를 하나의 타입으로 결합해요.
+type UserStore = UserStoreState & StoreSetters<UserStoreState>;
+
+// 결과 타입:
+// type UserStore = {
+//   id: number;
+//   name: string;
+//   age: number;
+//   setId: (value: number) => void;
+//   setName: (value: string) => void;
+//   setAge: (value: number) => void;
+// }
+```

docs/reference/built-in/Capitalize.md

@@ -1 +1,70 @@
-# Capitalize
+# Capitalize\<StringType>
+
+:::info
+The `Capitalize<StringType>` utility type is available starting from TypeScript version 4.1. For more information see in [TypeScript Handbook](https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html#uppercasestringtype), [Release Note](https://devblogs.microsoft.com/typescript/announcing-typescript-4-1/)
+:::
+
+## Overview
+
+The `Capitalize<StringType>` utility type capitalizes the first letter of a string literal type while keeping the remaining characters unchanged.
+
+## Syntax
+
+```ts
+type Capitalize<S extends string> = S extends `${inter F}${inter Rest}` ? `${Uppercase<F>}${Rest}` : S;
+```
+
+- **StringType (S)**: The string that you want to convert the first character to an uppercase equivalent.
+
+## Examples
+
+#### Example #1
+
+```ts
+type LowercaseGreeting = 'hello, world';
+type Greeting = Capitalize<LowercaseGreeting>; // 'Hello, world'
+```
+
+#### Example #2
+
+```ts
+type FormEventNames = 'submit' | 'reset' | 'change' | 'input' | 'focus' | 'blur' | 'invalid';
+type CapitalizedFormEventNames = Capitalize<FormEventNames>; // 'Submit' | 'Reset' | 'Change' | 'Input' | 'Focus' | 'Blur' | 'Invalid'
+type FormHandlerNames = `on${CapitalizedFormEventNames}`; // 'onSubmit' | 'onReset' | 'onChange' | 'onInput' | 'onFocus' | 'onBlur' | 'onInvalid'
+type FormHandlers = {
+  [FormHandlerName in FormHandlerNames]: (event: Event) => void;
+};
+```
+
+#### Example #3
+
+```ts
+interface UserStoreState {
+  id: number;
+  name: string;
+  age: number;
+}
+
+// Type to convert a property name to a setter function name.
+// For example, given 'name', it converts it to 'setName'.
+type ConvertToSetter<S extends string> = `set${Capitalize<S>}`;
+
+// Create a type for store setters based on the state.
+// For each property in StoreState, generate a setter function.
+type StoreSetters<StoreState> = {
+  [K in keyof StoreState as ConvertToSetter<Extract<K, string>>]: (value: StoreState[K]) => void;
+};
+
+// Combine the state and its setter into a single type.
+type UserStore = UserStoreState & StoreSetters<UserStoreState>;
+
+// Resulting type:
+// type UserStore = {
+//   id: number;
+//   name: string;
+//   age: number;
+//   setId: (value: number) => void;
+//   setName: (value: string) => void;
+//   setAge: (value: number) => void;
+// }
+```