docs: add user endpoint from backend

endpoint returns information about users using user/UUID or the special user/me endpoint

API/client-server/v1/user.md

@@ -0,0 +1,64 @@
+POST /v1/user/me
+POST /v1/user/{UUID}
+
+---
+
+Gathers information about the requested user.
+
+---
+
+## Request
+
+| Name         | Type   | Description                          |
+| ------------ | ------ | ------------------------------------ |
+| access_token | string | **Required**: The user's auth token. |
+
+
+```json
+{
+    "access_token": "85b2afece430e0e924f2d4277324c868",
+}
+```
+
+---
+
+## Responses
+
+| Status | Description                                     |
+| ------ | ----------------------------------------------- |
+| 200    | User data found.                                |
+| 400    | The post request included poorly formated data. |
+| 403    | Invalid access token.                           |
+| 500    | An unhandled error occured.                     |
+
+---
+
+### 200
+
+| Name         | Type   | Description                        |
+| ------------ | ------ | ---------------------------------- |
+| uuid         | string | UUID of the requested user         |
+| username     | string | Username of the requested user     |
+| display_name | string | Display Name of the requested user |
+
+```json
+{
+  "uuid": "7292d678-e718-4dbc-b2d5-e42a22abfdd6",
+  "username": "radial_4740",
+  "display_name": "Radial"
+}
+```
+
+---
+
+### 500
+
+| Name  | Type   | Description                      |
+| ----- | ------ | -------------------------------- |
+| error | string | The error the server encountered |
+
+```json
+{
+  "error": "Something went wrong!",
+}
+```