Packaging doc - make blurb about default packages directory more easily discoverable

[TraceyC77]

https://help.getsol.us/docs/packaging/prepare-for-packaging

This doc uses ~/solus-packages/ in a few places. The blurb about the name and where it is cloned is only under "Clone Your forked package repository". It can be easily missed if you're reading other sections.

Add a blurb to each section that references ~/solus-packages about this assumption.

Under "Initialize git hooks" this command fails on my system because my directory structure is different.

go-task -d ~/solus-packages init

On my host system, and dev VM, the directory is ~/packaging. This is the result of that command with that directory:

❯ go-task -d ~/packaging init                            ✘ 100 lua-5-4-6-rebuilds
task: No Taskfile found at "/home/tracey/packaging"

The document is not clear about what directory should be in that command. This works on my system

go-task -d ~/packaging/packages init

Similarly, the commands to set up the repo helper functions assume the location of the packages directory

ln -s ~/solus-packages/common/Scripts/helpers.sh ~/.bashrc.d/solus-monorepo-helpers.sh