Fix explanation of ignore-daemon-sets flag

[takanabe]

The ignore-daemon-sets flag is compatible with kubectl drain --ignore-daemonsets. It literally ignores daemon sets to proceed a drain. However, the description of ignore-daemon-sets flag says

If true, drain daemon sets when a spot interrupt is received.

This is the opposite meaning of what exactly this flag wants to do.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Merging #194 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #194   +/-   ##
=======================================
  Coverage   81.26%   81.26%           
=======================================
  Files          10       10           
  Lines         774      774           
=======================================
  Hits          629      629           
  Misses        129      129           
  Partials       16       16           

Impacted Files	Coverage Δ
pkg/config/config.go	100.00% <100.00%> (ø)

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[bwagner5]

Good catch! Thanks!!