refactor: rename "blacklist" -> "blocklist"

[nfischer]

No change to logic. This just renames "blacklist" to "blocklist" to use
more inclusive language.

Test: npm run test
Test: ./lib/cli.js exec (this is blocked, as expected)
Test: ./lib/cli.js help (does not mention blocked commands)

[codecov-commenter]

Codecov Report

Merging #193 (f86451c) into master (009e7bb) will not change coverage.
The diff coverage is 100.00%.

❗ Current head f86451c differs from pull request most recent head fb5d546. Consider uploading reports for the commit fb5d546 to get more accurate results

@@            Coverage Diff            @@
##            master      #193   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          114       114           
=========================================
  Hits           114       114           

Impacted Files	Coverage Δ
src/config.js	100.00% <100.00%> (ø)
src/help.js	100.00% <100.00%> (ø)
src/shx.js	100.00% <100.00%> (ø)

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