Rework "Normalize time series data intervals"

Hi there,

after reading @hammerhead's excellent [Interpolation of missing time series values](https://community.crate.io/t/interpolation-of-missing-time-series-values/659), I wonder if we should overhaul or even remove the [Interpolate missing records](https://crate.io/docs/crate/tutorials/en/latest/normalize-intervals.html#interpolate-missing-records) section within the [Normalize time series data intervals](https://crate.io/docs/crate/tutorials/en/latest/normalize-intervals.html) document.

Then, this document would be more like a Unix component in the terms of "_do one thing and do it well_" and I would rename it to "_Processing and plotting timeseries-data with CrateDB, Pandas and Matplotlib_" in order to better reflect its content.

What do you think about this?

With kind regards,
Andreas.

cc @proddata, @norosa