SRSF formula doc fix

[ego-thales]

See #530.

Sorry for the delay

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (b7e0023) 85.75% compared to head (2aee87b) 85.75%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #542 +/- ## ======================================== Coverage 85.75% 85.75% ======================================== Files 144 144 Lines 11428 11428 ======================================== Hits 9800 9800 Misses 1628 1628 ``` | [Impacted Files](https://app.codecov.io/gh/GAA-UAM/scikit-fda/pull/542?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GAA-UAM) | Coverage Δ | | |---|---|---| | [skfda/misc/metrics/\_fisher\_rao.py](https://app.codecov.io/gh/GAA-UAM/scikit-fda/pull/542?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GAA-UAM#diff-c2tmZGEvbWlzYy9tZXRyaWNzL19maXNoZXJfcmFvLnB5) | `98.78% <ø> (ø)` | | | [skfda/misc/operators/\_srvf.py](https://app.codecov.io/gh/GAA-UAM/scikit-fda/pull/542?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GAA-UAM#diff-c2tmZGEvbWlzYy9vcGVyYXRvcnMvX3NydmYucHk=) | `95.91% <ø> (ø)` | | | [skfda/preprocessing/registration/\_fisher\_rao.py](https://app.codecov.io/gh/GAA-UAM/scikit-fda/pull/542?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GAA-UAM#diff-c2tmZGEvcHJlcHJvY2Vzc2luZy9yZWdpc3RyYXRpb24vX2Zpc2hlcl9yYW8ucHk=) | `96.96% <ø> (ø)` | | | [skfda/preprocessing/registration/validation.py](https://app.codecov.io/gh/GAA-UAM/scikit-fda/pull/542?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GAA-UAM#diff-c2tmZGEvcHJlcHJvY2Vzc2luZy9yZWdpc3RyYXRpb24vdmFsaWRhdGlvbi5weQ==) | `98.78% <ø> (ø)` | |

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[vnmabus]

Sorry for the delay

You do not have to apologize. This is open source software, done in our free time, and nobody is entitled to our unpaid labor.

Thank you for the correction in the docs. However, I would say that the Newton notation for the derivative is not very widely used outside of the area of Differential Geometry. Thus, I would add a sentence such as "where $\dot{f}$ is the first derivative of $f$" or something like that. What do you think?

[ego-thales]

I would say that the Newton notation for the derivative is not very widely used outside of the area of Differential Geometry. Thus, I would add a sentence such as "where f˙ is the first derivative of f" or something like that. What do you think?

I agree completely. Personally, I would directly change all dots to apostrophes. I only tried to keep consistency. Let me know, I can update the PR.

[vnmabus]

I think that would be great, thank you!

[ego-thales]

I think that would be great, thank you!

There you go :ok_hand: