[Rule]: Expand acronym rule to check for full stops

[JC-DSIT]

Is this

• a suggestion for a new rule
• an update to an existing rule
• a suggestion to remove a rule

Why is this change important

Don’t use full stops in abbreviations or acronyms (error)

Examples of new behaviour as a result of the change

For example:

Scenario: Someone has created a page with a lot of new content, some of the words are over complicated
Given a page exists
And the page contains words from the words to avoid list
When the linter runs against the page with the "words to avoid" rule
Then the linter should fail

Add as many scenarios as you can think of to define the full behaviour of the rule. You can see existing examples in features/style_guide/*.feature