DOCTEAM-1776: intro to crmsh

[tahliar]

PR creator: Description

A basic intro article for the CRM Shell.

PDF:
HA-crmsh-introduction_en.pdf

PR creator: Are there any relevant issues/feature requests?

• jsc#DOCTEAM-1776

PR reviewer: Checklist for editorial review

Apart from the usual checks, please double-check also the following:

• do any new files fulfill the naming conventions specified in https://github.com/SUSE/doc-modular/blob/main/templates/README.md?
• article title/structure title: does it have the required length and does it use sentence style capitalization?
• revhistory: is it up-to-date and does it follow the guidelines specified in https://documentation.suse.com/style/current/html/style-guide-db/sec-smartdocs.html#sec-revhistory?
• metadata: does it follow the guidelines specified in https://documentation.suse.com/style/current/html/style-guide-db/sec-smartdocs.html#sec-taglist-smartdocs?