[Docs - LORIS installation] Updated installation instructions to reflect the requirement of PHP 8.0+

[jeffersoncasimir]

Brief summary of changes

• Modified the instructions to include the correct PHP library versions required for both Ubuntu and CentOS.
• Added the missing variable assignment to the section titled: 'Creating the lorisadmin user'.
• Changed an argument of the chown command in 'Creating the lorisadmin user' to prevent unwanted side-effects of creating a user with a period in its name.

Link(s) to related issue(s)

Resolves #8220

[christinerogers]

Thanks for this @jeffersoncasimir LGTM.
The missing variable assignment was originally intended to avoid picking the directory name for new projects, but it was definitely leading to some confusion based on comments heard over the years, so being more explicit should be helpful.

@driusan @ridz1208 any objections on specifying $projectname as loris as Jefferson has added here? It should reduce friction for new installs adn they can always change the name when they walk through these steps.

@kongtiaowang could you please pull and test, and review ? thanks

[driusan]

I don't have any strong opinions on the variable but if we're going to hardcode the value we might as well get rid of the variable and just hardcode the path that uses it.

[driusan]

@jeffersoncasimir ping.. are you going to get rid of the variable since it's hardcoded?

[jeffersoncasimir]

Yes, makes sense.