Add a 'Copy Snippet' button where applicable

**Is your feature request related to a problem? Please describe.**
Whenever I want to copy the code snippet for reverse proxy setup, I need to precisely select the whole code. It happened several times to copy the instruction too, or omit the initial bracket. This is also difficult to select desired code when using a mobile device.

**Describe the solution you'd like**
And add a 'Copy' button to have a code snippet copied to clipboard with a single click of a button.

**Describe alternatives you've considered**
There's nothing that comes to my mind.

**Additional context**