Added initial content on Observable Instances vs Observable Patterns
Initial commit on new Concept doc for Observable Instances vs Observable Patterns
Added the rest of the examples for the Observable Instances vs Observable Patterns section
Added new entry and links for Observable Instances vs Observable Patterns concept page
Modified the wording of the line about Test_MEchanism
Added a missing @condition to a field in the last example for Observable Instances vs Observable Patterns
Merge branch 'master' into Patterns_vs_Instances_42021

Conflicts:
	documentation/suggested-practices/index.md
Merge pull request #122 from STIXProject/Patterns_vs_Instances_42021

Patterns vs instances 42021