Add documentation for `renameToCamelCase`

[zaleslaw]

Add to the page https://kotlin.github.io/dataframe/rename.html the renameToCamelCase and particularExamples with toCamelCase in DSL

[zaleslaw]

@AndreiKingsley could you please have a look?

dataframe/core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/rename.kt

Line 57 in 6ee612c

* This function renames all columns in this [DataFrame] to the "camelCase" format.

- here are KDocs