update line and file count

[martinescardo]

There is a scriptcount-agda-files-and-lines which I suggest everybody should run before their pull requests, and then update index.lagda with this information.

Specifically, the snippet

   * In our last count, on 2024.06.19, this development has 761 Agda
     files with 215k lines of code, including comments and blank
     lines. But we don't update the count frequently.

should perhaps always be updated in any pull request.

It would be even better if there was an automatic way of doing this.

Then we could omit "But we don't update the count frequently.".

[ayberkt]

It would be even better if there was an automatic way of doing this.

It is possible to automate it and I would be happy to implement it. It should be relatively easy to do.