DOC: interpolate.FloaterHormannInterpolator: fix typos

[j-bowhay]

No description provided.

[mdhaber]

While we're at it:

Due to its stability following barycentric representation of the above equation is used instead for computation

Should that be:

Due to its stability, the following barycentric representation of the above equation is used for computation

?

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is an interpolating polynomials of at

Maybe polynomial should be singular.

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Is values supposed to be y?

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Perhaps the plot in the examples should show the original curve as a solid line, and the interpolators can be dashed.

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Consider

d : int, default: 3
    Integer satisfying ``0 <= d < n``. Floater-Hormann interpolation blends
    ``n - d`` polynomials of degree `d` together; for ``d = n - 1``, this is
    equivalent to polynomial interpolation.