[perfect-numbers] Join broken line and add colon

[habere-et-dispertire]

As per @kotp 's suggestions on track raku :

exercism/raku#669

[github-actions]

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[habere-et-dispertire]

@IsaacG : It's "equal to" not "equals to", right ?

[IsaacG]

@IsaacG : It's "equal to" not "equals to", right ?
"is equal to" or "equals"

[kotp]

Approving, with a small suggestion to complete a sentence with a period.