Fix N+1 error message

The error contained a typo and is slightly cumbersome. It changes from:

- ERROR: node a: not enough memory on to accommodate failovers should peer node
  b fail

to:

- ERROR: node a: not enough memory to accomodate instance failovers should node
  b fail

Signed-off-by: Miguel Di Ciurcio Filho <miguel.filho@gmail.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>