docs: Add description to video stream converter

### Describe the bug
Swagger should explain what are acceptable formats for stream converter
Endpoint should take youtube video id as argument and return stream by selected format:

### To Reproduce
Steps to reproduce the behaviour:
1. Go to https://stem-diverse-tv.herokuapp.com/
2. Click on GET /videos/stream/{videoId}/{format}
3. See there is no description about available formats

### Expected behaviour
Show available formats as below
```
249 - audio only (DASH audio), webm, 50
250 - audio only (DASH audio), webm, 70
171 - audio only (DASH audio), webm, 128
140 - audio only (DASH audio), m4a, 128
251 - audio only (DASH audio), webm, 160
141 - audio only (DASH audio), m4a, 256
278 - 256x144 (DASH video), webm,
160 - 256x144 (DASH video), mp4,
242 - 426x240 (DASH video), webm,
133 - 426x240 (DASH video), mp4,
243 - 640x360 (DASH video), webm,
134 - 640x360 (DASH video), mp4,
244 - 854x480 (DASH video), webm,
135 - 854x480 (DASH video), mp4,
247 - 1280x720 (DASH video), webm,
136 - 1280x720 (DASH video), mp4,
248 - 1920x1080 (DASH video), webm,
137 - 1920x1080 (DASH video), mp4,
17 - 176x144 (small), 3gp,
36 - 320x240 (small), 3gp,
5 - 400x240 (small), flv,
43 - 640x360 (medium), webm,
18 - 640x360 (medium), mp4,
22 - 1280x720 (hd720), mp4,
```

### Screenshots

### Desktop (please complete the following information):
- OS: Any
- Browser: Any
- Version: Any

### Smartphone (please complete the following information):
- Device: Any
- OS: Any
- Browser: Any
- Version: Any