fix unCamelcase

[ljwrer]

if text contains number,like i18n,expect to get i18n rather than i-1-8n #15

[coveralls]

Coverage decreased (-0.001%) to 99.628% when pulling c48b229 on ljwrer:master into 1de6608 on vuedoc:master.

[demsking]

Thanks @ljwrer for your feedback. Could you just add a test that cover this case please?
Something like:

it('should succeed with entry that contains numbers', () => {
  const entry = 'i18n'
  const result = utils.unCamelcase(entry)
  const expected = 'i18n'

  assert.equal(result, expected)
})

[coveralls]

Coverage decreased (-0.001%) to 99.628% when pulling 76eae1c on ljwrer:master into 1de6608 on vuedoc:master.

[ljwrer]

test case added @demsking

[demsking]

Great!
Thanks for your PR. I'll release it soon