[DOC] Typo present in getting start guide: Redundant use of 'n_timepoints'

[IRKnyazev]

Describe the issue linked to the documentation

Under the section Understanding time series data:

We commonly refer to the number of observations for a time series as n_timepoints or n_timepoints. If a series is multivariate, we refer to the dimensions as channels (to avoid confusion with the dimensions of array) and in code use n_channels. Dimensions may also be referred to as variables.

This paragraph provides the same term twice as alternatives for describing the number of observations.

**Edit: found a small typo further down: Collections of time series may also be referred to a Panels. Collections of time series will often be accompanied by an array of target variables.

Suggest a potential alternative/fix

Either remove the second option of 'n_timepoints' or provide a correct alternative term.

**Edit: second typo should be corrected to ' Collections of time series may also be referred to as Panels....'

[IRKnyazev]

Aeon-Assign bot assign @IRKnyazev

[TonyBagnall]

@IRKnyazev assume #1842 should have closed this, typo on the PR number

[IRKnyazev]

@IRKnyazev assume #1842 should have closed this, typo on the PR number

@TonyBagnall Oops yes sorry 😬