Heat break curling issue

[Fuechsl]

You wrote it in the very last sentence in readme.md. I had this issue, it caused clogs and took me endless time to figure it our. Thus, I propose to write more about this potential problem in bold letters as in:

Be very careful not to overtight the three titanium alloy screws. If not, you may curl the upper part of the heat break which leads to filament jamming and clogging. It is better to use the grub screw and the little "plug core" (called like this by phaetus) to fix the heater part in position and tighten the three titanium alloy screws just snug.