[DOCUMENTATION] - improve searchability and visibility of Regrid instructions

[FransRoelofsen]

When you search for Regrid on the github page, you end up at the more complex use case, namely regridding entire models or packages.

For grid-level applications, the first relevant search result with Regrid in the title appears much further down the list:
https://deltares.github.io/imod-python/user-guide/08-regridding.html

Even on that page, the focus quickly shifts to regridding models. The page does start with a paragraph about working with individual scripts, and then states:

“More information on the available regridding methods can be found in the xugrid documentation
[https://deltares.github.io/xugrid/user_guide.html”](https://deltares.github.io/xugrid/user_guide.html”)

This link does not quite lead to the most relevant page.

Suggestion: could this link be changed to
https://deltares.github.io/xugrid/examples/regridder_overview.html ?

What you actually want users to find in the iMOD Python documentation is this paragraph:
https://deltares.github.io/imod-python/faq/how-do-i/index.html#change-cellsize-and-extent

Suggestion: if the word “regrid” is included in the paragraph title, it will also show up in search results.

Proposed title:
“Change cellsize and/or extent (Regridding)”

In addition:

• consider adding the 3rd option "BarycentricInterpolator"
• consider adding a list of possible methods with the option "OverlapRegridder"