improve readme

[alex-free]

• Removed unneccesary john@localhost:ps5-payload-dev/sdk$ from commands. Now you can copy each line or entire chunks into a terminal without issue.

• Moved dependencies for working with decrypted sprx files to 'optional' dependency lines, because they are optional and if your already installing optional stuff why not just do it all at once.

• Change wget to required dependency, since it actually is needed in ./libcxx.sh.

• Added Fedora and Mac OS dependencies for for working with decrypted sprx files.

• In usage section, changed export PS5_HOST=ps5 to export PS5_HOST=ps5_ip_address for clarity on this needing to be replaced in example.

• In building sdk section, add sudo to make DESTDIR=/opt/ps5-payload-sdk install, since without it we don't have write privlages to /opt and command fails.

• In building sdk section, add sudo -E to ./libcxx.sh # fetch, build, and install libcxx since again, we do not have write privlages to /opt without it and the command fails. the -E flag tells sudo to keep the envars already set by current user in that context.

• In adding new SCELibs section, add sudo to make DESTDIR=/opt/ps5-payload-sdk install because again, we do not have write privlages to /opt without it and the command fails.