Fix some ATT&CK verbiage and trademark

[rw-access]

I saw some verbiage for threat.* that mentioned the MITRE ATT&CK® framework but needed to be adjusted.

Some of the changes

• Added ®. We were supposed to have ™ before, but early in 2020 they were granted ®.
• Correctly spelled MITRE with all capital letters
• Removed some confusing verbiage like "You can use the Mitre ATT&CK Matrix Tactic categorization." The words "Tactic categorization" are a little confusing and not part of the framework. Instead I went with "You can use a MITRE ATT&CK Matrix® tactic, for example." Also, it's possible to mention tactics without concrete techniques and vice versa, so I removed any language that coupled them together.

[webmat]

Thanks for submitting this, @rw-access!

One small nitpick, see comment below. Otherwise LGTM :-)

[webmat]

I would switch the phrasing "use a" instead of "use the" for this sentence as well.

[rw-access]

thank you! this is why we peer review 😆