chore: add api docs (#1965)

docs/api/memo.md

@@ -0,0 +1,135 @@
+# Memo APIs
+
+## Create Memo
+
+```
+POST /api/v1/memo
+```
+
+**Request Body**
+
+```json
+{
+  "content": "Memo content",
+  "visibility": "PUBLIC",
+  "resourceIdList": [123, 456],
+  "relationList": [{ "relatedMemoId": 789, "type": "LINK" }]
+}
+```
+
+**Response**
+
+```json
+{
+  "id": 1234,
+  "content": "Memo content",
+  "visibility": "PUBLIC"
+  // other fields
+}
+```
+
+**Status Codes**
+
+- 200: Created
+- 400: Invalid request
+- 401: Unauthorized
+- 403: Forbidden to create public memo
+- 500: Internal server error
+
+## Get Memo List
+
+```
+GET /api/v1/memo
+```
+
+**Parameters**
+
+- `creatorId` (optional): Filter by creator ID
+- `visibility` (optional): Filter visibility, `PUBLIC`, `PROTECTED` or `PRIVATE`
+- `pinned` (optional): Filter pinned memo, `true` or `false`
+- `tag` (optional): Filter memo with tag
+- `content` (optional): Search in content
+- `limit` (optional): Limit number of results
+- `offset` (optional): Offset of first result
+
+**Response**
+
+```json
+[
+  {
+    "id": 1234,
+    "content": "Memo 1"
+    // other fields
+  },
+  {
+    "id": 5678,
+    "content": "Memo 2"
+    // other fields
+  }
+]
+```
+
+## Get Memo By ID
+
+```
+GET /api/v1/memo/:memoId
+```
+
+**Response**
+
+```json
+{
+  "id": 1234,
+  "content": "Memo content"
+  // other fields
+}
+```
+
+**Status Codes**
+
+- 200: Success
+- 403: Forbidden for private memo
+- 404: Not found
+- 500: Internal server error
+
+## Update Memo
+
+```
+PATCH /api/v1/memo/:memoId
+```
+
+**Request Body**
+
+```json
+{
+  "content": "Updated content",
+  "visibility": "PRIVATE"
+}
+```
+
+**Response**
+
+Same as **Get Memo By ID**
+
+**Status Codes**
+
+- 200: Updated
+- 400: Invalid request
+- 401: Unauthorized
+- 403: Forbidden
+- 404: Not found
+- 500: Internal server error
+
+## Delete Memo
+
+```
+DELETE /api/v1/memo/:memoId
+```
+
+**Status Codes**
+
+- 200: Deleted
+- 401: Unauthorized
+- 403: Forbidden
+- 404: Not found
+- 500: Internal server error