Install commands in README copies the % sign when you use copy button

In https://github.com/astropy/astropy-workshop/blob/main/00-Install_and_Setup/README.md , when user use the copy icon/button (right side of the command line), it also copies the `%`, which would cause error on the terminal.

Example: `% conda info`

Desired outcome:

a. Remove `%` from the examples, OR
b. Have some magic so the copy icon/button ignores the `%` on copy.

cc @mwcraig @eteq 