Fix file names and permissions

[redhatrises]

• Add file permissions constants
• Files shouldn't be executable
• Files shouldn't use spaces in file names for multi-OS support

[codecov]

Codecov Report

Merging #323 into master will decrease coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #323      +/-   ##
==========================================
- Coverage   79.09%   79.06%   -0.03%     
==========================================
  Files          38       38              
  Lines        1430     1428       -2     
==========================================
- Hits         1131     1129       -2     
  Misses        246      246              
  Partials       53       53

Impacted Files	Coverage Δ
pkg/cli/docs/gitbook/gitbook.go	80% <ø> (-1.82%)	⬇️
pkg/cli/docs/gitbook/gitbookSummaries.go	90.47% <100%> (ø)	⬆️
pkg/cli/docs/gitbook/gitbookComponents.go	100% <100%> (ø)	⬆️
pkg/cli/docs/gitbook/gitbookCertification.go	95.18% <100%> (ø)	⬆️

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[shawndwells]

Quick skim: function names need consistent capitalization. replaceParentheses vs FileNameHandler

[redhatrises]

@shawndwells exported function names are capitalized e.g. FileNameHandler. Non-exported function names are not capitalized e.g. replaceParentheses. The function names are using correct Golang syntax. See https://stackoverflow.com/questions/38616687/which-way-to-name-a-function-in-go-camelcase-or-semi-camelcase

[shawndwells]

thanks @redhatrises