Update all docs for new templates

[qbzzt]

Merged:

• hello / add table (docs(guide/hello/add-table): update to account for the namespace change 🚗  #2855)
• hello / add system (docs(guides/hello/add system): update for the app namespace 🚗  #2859)

In Review:

• hello / filter (docs(guides/hello/filter): update for app namespace 🚗  #2858)
• extending (docs(guides / extending): update for the app namespace 🚗  #2860)

Not needed:

• hello / deploy no changes needed
• delegation no changes needed