dnsmap: add page

[Faro1991]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page(s) have at most 8 examples.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known):
  0.36 (ref: https://www.kali.org/tools/dnsmap/)

[tldr-bot]

The build for this PR failed with the following error(s):

pages/linux/dnsmap.md:
Error: Parse error on line 4:
...rce-projects/dnsmap>- Scan for subdoma
-----------------------^
Expecting 'END_INFORMATION_LINK_URL', got 'NEWLINE'
pages/linux/dnsmap.md:3: TLDR003 Descriptions should start with a capital letter
pages/linux/dnsmap.md:3: TLDR004 Command descriptions should end in a period
pages/linux/dnsmap.md:4: TLDR011 Page never contains more than a single empty line

Please fix the error(s) and push again.

[tldr-bot]

The build for this PR failed with the following error(s):

pages/linux/dnsmap.md:
Error: Parse error on line 4:
...rce-projects/dnsmap>- Scan for subdoma
-----------------------^
Expecting 'END_INFORMATION_LINK_URL', got 'NEWLINE'
pages/linux/dnsmap.md:3: TLDR004 Command descriptions should end in a period
pages/linux/dnsmap.md:4: TLDR011 Page never contains more than a single empty line

Please fix the error(s) and push again.

[Faro1991]

Related to #6863

[kbdharun]

LGTM, Thanks for your contribution.

[Dagidani]

Nais