Build instructions: update configure to use specific gcc versions

[pedropintosilva]

gcc/g++ must be at least version 12 that means that on core (building LO) we need to use that see https://wiki.documentfoundation.org/Development/BuildingOnLinux#openSUSE and on online the same goes.

• Add CC="ccache gcc-12" CXX="ccache g++-12" flags to the ./configure line under building online for each distro if needed
• Test it

[omkarhole]

Hey @pedropintosilva I would like to contribute . can you please assign me ?

[pedropintosilva]

Done, but the contribution needs to be done in the wiki.

[omkarhole]

Hii @pedropintosilva i have created PR Link Please review it