Add --no-escape flag for Markdown printer

[khos2ow]

Prerequisites

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• This pull request fixes a bug.
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For more information, see the Contributing Guide.

Description

This PR adds a new flag --no-escape to markdown (also its alias: md) commands to not escaping special characters. The issue has been discussed at length at #111 .

Note that the default behavior is that Markdown printer escapes the characters and you need to explicitly tell terraform-doc to not escape them.

Issues Resolved

Fixes #111

Checklist

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Tests

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[khos2ow]

@metmajer Since "escaping" is now a new concept, I've changed the test golden files to be in normal non-escaped state and added a new file with escaped characters.

[metmajer]

@khos2ow thanks for the PR, I'll provide some feedback over the next days!

[metmajer]

@khos2ow if escaping is the default (escaping has to be disabled explicitly using --no-escape-flag), why are the existing golden files not in the escaped state then? These should reflect the default case. From your explanations, however, I understand that this is not the case?

[khos2ow]

@metmajer sorry for the delay. It indeed is disabled by default (set here).

All the existing golden files and corresponding test cases follow the same approach and I didn't want to change the logic in only one test. I mean flags --no-required and --no-sort are disabled by default but we explicitly enable them only in their corresponding test cases (TestPrintWithRequired and TestPrintWithSortByName) and this is the same case for --no-escape and TestPrintWithEscapeName.

[metmajer]

@khos2ow likewise, and thanks. I should have taken the time to double-check on our default behavior. Current projects are keeping me busy like crazy. Cheers!