Clean up migration guide to remove some marketing verbiage

For a more extended description: 

#6816

source/onboard/migrating-to-mattermost.rst

@@ -66,38 +66,6 @@ Sometimes systems running in parallel turn into a hard switch migration when a b
 
 When IT adopts management of Mattermost, often they will purchase the commercial version for additional compliance, access control, and scale features, in addition to high quality commercial support for upgrades and migrations. Teams can `purchase Mattermost Enterpise Edition with a credit card online <https://mattermost.com/pricing-self-managed/>`__ or `contact sales <https://mattermost.com/contact-us/>`__ to engage in an enterprise procurement process.
 
-Why IT teams choose to leave bespoke solutions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Because messaging solutions in technical teams often contain confidential and highly exploitable data, messaging solutions become a security concern that could impact all of an organization's technical infrastructure.
-
-When IT teams are asked to maintain a bespoke messaging solution, they often need to consider security issues such as the following:
-
-1. Is the solution backed by a commercial entity with significant legal obligations to ensure the safety and security of the product?
-2. Is there a security bulletin available to alert our organization of high-priority security updates, with clear instructions to apply the updates?
-3. Does the solution have a clear and up-to-date list of security updates?
-4. Are security updates released prior to detailed disclosure of vulnerability details, so as to provide our organization with time to apply security updates before vulnerabilities are widely known?
-5. In addition to internal testing, is there a Responsible Disclosure Policy for external security researchers to confidentially report security issues, and a recognition program for their contributions?
-
-Bespoke communication products that provide weak security assurance can dramatically increase the risk to IT teams and their organizations.
-
-When early adopters of a bespoke solutions ask IT to "take over" and assume the risk of managing a rapidly installed, difficult-to-maintain system with limited or no assurance of security, the IT team is under a great deal of pressure.
-
-Often at this point, IT teams accelerate their exploration of Mattermost as a long-term solution, given the `thousands of organizations (many in mission critical, high security industries) that have switched <https://mattermost.com/customers/>`__.
-
-Why IT teams choose Mattermost over bespoke solutions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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-Mattermost is designed to replace bespoke messaging solutions through a platform that is unmatched in flexibility. From the `hundreds of open source projects extending and customizing Mattermost through APIs and drivers <https://github.com/search?utf8=✓&q=mattermost&type=>`__, to an innovative client and server plugin framework for adapting the Mattermost user experience to the specific workflows and needs, thousands of high performance teams rely on Mattermost daily.
-
-In addition, IT teams prefer Mattermost for its specific `security assurances </about/security.html>`__:
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-1. Mattermost products are backed by Mattermost, Inc., which has commercial contracts with hundreds of enterprises around the world, many with Fortune 500 and Global 2000 organizations who require significant obligations and assurances from vendors of critical infrastructure.
-2. Mattermost offers a `security bulletin <https://mattermost.com/security-updates/#sign-up>`__ to alert IT teams and customers of high priority security updates, with step-by-step instructions for upgrade and options for commercial support.
-3. Mattermost maintains an `up-to-date list of security updates <https://mattermost.com/security-updates/>`__ for both its open source and commercial offerings.
-4. To keep IT teams safe, Mattermost waits 14 days after releasing a security patch before disclosing the specific details of the vulnerability each addresses.
-5. A `Responsible Disclosure Policy <https://mattermost.com/security-vulnerability-report/>`__ is available to supplement internal security reviews with confidential reports from external security researchers, with a recognition program for security research contributions after the security patch is properly released.
-
 ----
 
 Migrate Mattermost server
@@ -121,4 +89,4 @@ The following instructions migrate Mattermost from one server to another by back
 7. Start the DESTINATION deployment by running ``sudo start mattermost``. Then go to the **System Console**, make a minor change, and save it to upgrade your ``config.json`` schema to the latest version using default values for any new settings added.
 8. Test that the system is working by going to the URL of an existing team. You may need to refresh your Mattermost browser page in order to get the latest updates from the upgrade.
 
-Once your migration is complete and verified, you can optionally `upgrade the Team Edition of Mattermost to Enterprise Edition using the upgrade guide </upgrade/upgrading-mattermost-server.html#upgrading-team-edition-to-enterprise-edition>`__.
+Once your migration is complete and verified, you can optionally `upgrade the Team Edition of Mattermost to Enterprise Edition using the upgrade guide </upgrade/upgrading-mattermost-server.html#upgrading-team-edition-to-enterprise-edition>`__.