Remove comments from jh image creation doc

[Shreyanand]

In this section of the doc, line To get image built by Thoth (in Tekton?) (not sure what is the right formulation here) seems to have comments in the brackets that should be removed (unless I'm missing something here).

[MichaelClifford]

This whole doc is fairly old. Does it need to a more robust update to ensure it matches with our current process?

[chauhankaranraj]

This whole doc is fairly old. Does it need to a more robust update to ensure it matches with our current process?

IMO the process is mostly still the same, but the doc could surely use some updates :)