Add the ability to print some label as a column

[marcelofernandez]

Hi!
I'd like to have the possibility to print out some label value (like beta.kubernetes.io/instance-type) along the rest of the node data, like this:

$ kubectl resource-capacity --show-label "beta.kubernetes.io/instance-type"
NODE                                            CPU REQUESTS   CPU LIMITS       MEMORY REQUESTS   MEMORY LIMITS    beta.kubernetes.io/instance-type
*                                               29695m (62%)   116800m (245%)   126647Mi (40%)    379666Mi (121%)  *
ip-10-210-1-115.us-east-1.compute.internal   5075m (31%)    18300m (115%)    25870Mi (41%)     51144Mi (81%) t3.medium
ip-10-210-1-82.us-east-1.compute.internal    6035m (76%)    26900m (340%)    26672Mi (42%)     93640Mi (150%) t3.medium
ip-10-210-3-174.us-east-1.compute.internal   5435m (68%)    19000m (240%)    20781Mi (33%)     71265Mi (114%) t3.small
ip-10-210-3-89.us-east-1.compute.internal    5975m (75%)    26300m (332%)    26432Mi (42%)     92104Mi (147%) t3.large
ip-10-210-8-230.us-east-1.compute.internal   7175m (90%)    26300m (332%)    26894Mi (43%)     71513Mi (114%) g4dn.xlarge

What do you think about this (sorry about the formatting)? is this feasible?

Thank you!