Fix/copypasta dashboard labels

[artulidis]

Updated n-gram statistics and data viewer cards on the dashboard.

Pull Request type

Please check the type of change your PR introduces:

• Bugfix
• [ X] Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build-related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue Number: #257

What is the new behavior?

On the N-gram statistics card:

• Renamed "N-gram statistics" card header to "Copypasta Statistics"
• Renamed X and Y axis labels
• Added a chart explanation below the X-axis label

On the Data viewer card:

• Renamed "Data viewer" card header to "N-gram Details Viewer"
• Broke down n-gram detail text into three lines: "N-gram", "No. total repetitions", and "No. unique UserIDs"
• Capitalized column labels

Does this introduce a breaking change?

• Yes
• [ X] No