Missing video dependency requirements on Readme

[BedHedd]

• I have read the FAQ.
• I have searched in existing issues.

Environment

• OS: Fedora 33
• scrcpy version: 1.18
• installation method: copr
• device model: Realme XT (RMX1921)
• Android version: Android 10

Describe the bug
Hello I noticed that in the readme/faq that there wasn't any instructions to install additional video dependency. If the dependencies are missing on a user's computer, they won't be able to install the package. You can see which dependencies are missing in the terminal outputs section.

I found that installing ffmpeg seemed to install any missing video dependencies. The following guide was helpful in installing ffmpeg
https://computingforgeeks.com/how-to-install-ffmpeg-on-fedora/

The solution is to have the package install with the video dependencies, or have a section listing the codec requirements and how to install them.

terminal output

sudo dnf install scrcpy
Copr repo for scrcpy owned by zeno               10 kB/s | 2.4 kB     00:00    
Error: 
 Problem: conflicting requests
  - nothing provides libavcodec.so.58()(64bit) needed by scrcpy-1.18-2.fc33.x86_64
  - nothing provides libavcodec.so.58(LIBAVCODEC_58)(64bit) needed by scrcpy-1.18-2.fc33.x86_64
  - nothing provides libavdevice.so.58()(64bit) needed by scrcpy-1.18-2.fc33.x86_64
  - nothing provides libavdevice.so.58(LIBAVDEVICE_58)(64bit) needed by scrcpy-1.18-2.fc33.x86_64
  - nothing provides libavformat.so.58()(64bit) needed by scrcpy-1.18-2.fc33.x86_64
  - nothing provides libavformat.so.58(LIBAVFORMAT_58)(64bit) needed by scrcpy-1.18-2.fc33.x86_64
  - nothing provides libavutil.so.56()(64bit) needed by scrcpy-1.18-2.fc33.x86_64
  - nothing provides libavutil.so.56(LIBAVUTIL_56)(64bit) needed by scrcpy-1.18-2.fc33.x86_64
(try to add '--skip-broken' to skip uninstallable packages)
$ sudo dnf install scrcpy --skip-broken

[rom1v]

Error: 
Problem: conflicting requests
 - nothing provides libavcodec.so.58()(64bit) needed by scrcpy-1.18-2.fc33.x86_64

-1.18-2.fc33.x86_64

That's not missing codec, but just missing dependencies (ffmpeg) managed by your package manager.

[BedHedd]

Thanks! I'll update the title