Update RPT_Blockquote_HasCite rule messages

[shunguoy]

The "RPT_Blockquote_HasCite", renamed to blockquote_cite_exists rule checks if a "blockquote" element has a "cite" attribute or one or more "cite" element(s) as its child(ren). However, the rule messages don't reflect what the rule actually checks:

  `
        "Pass_0": "Rule Passed",
        "Potential_1": "Verify that <blockquote> is used only for quotations, not indentation",
        "group": "Use <blockquote> only for quotations, not indentation"
  ` 

See box note for discussion and proposed changes
blockquote_cite_exists

Will affect the rule logic.ts, help.html, and ruleunit test cases files

[aliunwala]

Triage:
Help/Message do not correctly state what is happening. This needs to be reworded.

The new message will be similar to:
"Verify if blockquote has cite attribute or cite child elements"

The test cases/baselines will need to be updated

[philljenkins]

Current help page for blockquote_cite_exists

[philljenkins]

Working on two other higher-priority issues before this one

[philljenkins]

Rule was renamed to blockquote_cite_exists.ts
"Potential_1": "Verify that <blockquote> should not be used only for quotations, not indentation",
"group": "Use <blockquote> only for quotations, not indentation"

See box note for discussion and proposed changes
blockquote_cite_exists rule

[philljenkins]

reviewed changes in the team Showcase

[philljenkins]

... or child element

was removed from the message and help content since no HTML examples use the <cite> element as children of <blockquote>. All the examples shown are used separately from <blockquote>, so only the attribute is mentioned in the message and help.