Fix several issues in docs/consistency-model.md
Fix several issues in docs/consistency-model.md

- Clarify that some operations don't care about the dirty bit

- Use 'apply' rather than 'deploy'

- Clarify failure mode and idempotency of 'project_apply'

- Fix description of 'node_{attach,detach}_network'

- Document limitation of 'headnode_delete'

- Needlessly reindent paragraph for 'headnode_power_{on,off}'

henn/hil,kylehogan/haas,CCI-MOC/haas,SahilTikale/switchHaaS,kylehogan/hil,henn/hil_sahil,lokI8/haas,henn/hil,meng-sun/hil,apoorvemohan/haas,henn/hil_sahil,henn/haas,apoorvemohan/haas,meng-sun/hil,SahilTikale/haas,kylehogan/hil