Typo fix

[alanmcanonical]

Request type

Fix

What needs to get done

At here Please not that this level of customisation is only needed when you want to install from a custom Chisel release. , maybe the not is a typo which actually means note?

Documentation location

https://documentation.ubuntu.com/rockcraft/en/latest/how-to/chisel/install-slice/

Additional information

No response