feat(docs): update collection api doc

docs/reference/collection.md

@@ -4,14 +4,234 @@ toc: menu
 
 # Collection
 
-## collection.constructor()
-## collection.mergeOptions()
-## collection.sync()
-## collection.hasField()
-## collection.getField()
-## collection.addField()
-## collection.setFields()
-## collection.mergeField()
-## collection.removeField()
-## collection.forEachField()
-## collection.findField()
+## `collection.addField()`
+
+添加字段，如果字段 name 已存在，直接替换。
+
+##### Definition
+
+```ts
+interface addField {
+  (name: string, options: FieldOptions): Field;
+}
+```
+
+##### Examples
+
+```ts
+const field = collection.addField('name1', {
+  type: 'string',
+});
+await field.sync();
+```
+
+## `collection.findField()`
+
+##### Definition
+
+```ts
+interface findField {
+  (fn: (field: Field) => boolean): Field;
+}
+```
+
+##### Examples
+
+```ts
+const field = collection.findField((field) => {
+  return field.name === 'name1';
+});
+```
+
+## `collection.forEachField()`
+
+##### Definition
+
+```ts
+interface forEachField {
+  (fn: (field: Field) => void): void;
+}
+```
+
+##### Examples
+
+```ts
+collection.forEachField((field) => {
+
+});
+```
+
+## `collection.getField()`
+
+获取字段
+
+##### Definition
+
+```ts
+interface getField {
+  (name: string): Field;
+}
+```
+
+##### Examples
+
+```ts
+const field = collection.getField('name');
+```
+
+## `collection.hasField()`
+
+是否存在某字段
+
+##### Definition
+
+```ts
+interface hasField {
+  (name: string): boolean;
+}
+```
+
+##### Examples
+
+```ts
+collection.hasField('name');
+```
+
+## `collection.updateOptions()`
+
+更改当前 collection 的 options
+
+##### Definition
+
+```ts
+interface updateOptions {
+  (options: CollectionOptions): void;
+}
+```
+
+##### Examples
+
+```ts
+const collection = db.collection({
+  name: 'tests',
+});
+
+collection.updateOptions({
+  createdAt: true,
+  updatedAt: true,
+  sortable: true,
+  fields: [],
+});
+```
+
+## `collection.removeField()`
+
+移除字段
+
+##### Definition
+
+```ts
+interface removeField {
+  (name: string): Field;
+}
+```
+
+##### Examples
+
+```ts
+collection.removeField('name');
+```
+
+## `collection.setFields()`
+
+设置 fields，会清空之前配置的 fields。
+
+##### Definition
+
+```ts
+interface setFields {
+  (fields: FieldOptions[]): void;
+}
+```
+
+##### Examples
+
+```ts
+const collection = db.collection({
+  name: 'tests',
+});
+collection.setFields([
+  { type: 'string', name: 'name1' },
+  { type: 'string', name: 'name2' },
+]);
+```
+
+## `collection.sync()`
+
+##### Definition
+
+```ts
+interface sync {
+  (options?: SyncOptions): Promise<void>;
+}
+```
+
+##### Examples
+
+如果关联表不存在，不处理
+
+```ts
+const Post = db.collection({
+  name: 'posts',
+  fields: [
+    { type: 'string', name: 'name' },
+    // tags 跳过
+    { type: 'belongsToMany', name: 'tags' },
+  ],
+});
+await Post.sync();
+```
+
+如果关系表存在，一起处理
+
+```ts
+const Post = db.collection({
+  name: 'posts',
+  fields: [
+    { type: 'string', name: 'name' },
+    { type: 'belongsToMany', name: 'tags' },
+  ],
+});
+const Tag = db.collection({
+  name: 'tags',
+  fields: [{ type: 'string', name: 'name' }],
+});
+await Post.sync();
+// 等同于
+await db.sequelize.models.posts.sync();
+await db.sequelize.models.tags.sync();
+await db.sequelize.models.posts_tags.sync();
+```
+
+## `collection.updateField()`
+
+更新字段配置
+
+##### Definition
+
+```ts
+interface updateField {
+  (name: string, options: FieldOptions): Field;
+}
+```
+
+##### Examples
+
+更改 name
+
+```ts
+const field = collection.updateField('name1', {
+  name: 'name2',
+});
+await field.sync();
+```