mssql_login documentation added.

[AleksaZatezalo]

Working on auxilary scanner docs. Issue #12389. Added documentation for mssql_login.

Verification

Steps needed to make things work are as follows:

• Start msfconsole
• run msf> use scanner/mssql/mssql_login
• run msf> info -d
• Verify that you see proper documentation

[jheysel-r7]

Thanks for the PR @AleksaZatezalo!! I've added a few suggestions around general formatting. I've also added a ### Setup section section under ## Vulnerable Application outlining how users can spin up a target to test this module.

One very useful tool when writing metasploit documentation is the tools/dev/msftidy_docs.rb. It can be run like so and provides important information with regards to formatting:

➜  metasploit-framework git:(1bd7d25088) ruby tools/dev/msftidy_docs.rb documentation/modules/auxiliary/scanner/mssql/mssql_login.md
documentation/modules/auxiliary/scanner/mssql/mssql_login.md - [WARNING] Please add a newline at the end of the file
documentation/modules/auxiliary/scanner/mssql/mssql_login.md:3 - [WARNING] Spaces at EOL
documentation/modules/auxiliary/scanner/mssql/mssql_login.md:6 - [WARNING] Instructional text not removed
documentation/modules/auxiliary/scanner/mssql/mssql_login.md:9 - [WARNING] Should use single backquotes (`) for single line literals instead of triple backquotes (```)
documentation/modules/auxiliary/scanner/mssql/mssql_login.md:10 - [WARNING] Should use single backquotes (`) for single line literals instead of triple backquotes (```)
documentation/modules/auxiliary/scanner/mssql/mssql_login.md:11 - [WARNING] Should use single backquotes (`) for single line literals instead of triple backquotes (```)
documentation/modules/auxiliary/scanner/mssql/mssql_login.md:15 - [WARNING] Spaces at EOL
documentation/modules/auxiliary/scanner/mssql/mssql_login.md:16 - [WARNING] Spaces at EOL

msftidy_docs.rb should always be run before submitting docs files. I've went ahead and applied the fixes to the above warnings.

[bwatters-r7]

Release Notes

This PR adds documentation for the mssql_login module.