fix deprecation message; add renaming to the examples

[pawelru]

before:

r$> lifecycle::deprecate_soft("0.6.1", "datanames()", details = "names()")
Warning message:
`datanames()` was deprecated in <NA> 0.6.1.
ℹ names()

after:

r$> lifecycle::deprecate_soft("0.6.1", "datanames()", with = "names()")
Warning message:
`datanames()` was deprecated in <NA> 0.6.1.
ℹ Please use `names()` instead.

Also updated docs to give example of reassigning names - previously done with datanames(x) <- ... which is deprecated now

[github-actions]

Unit Tests Summary

  1 files   15 suites   1s ⏱️
163 tests 163 ✅ 0 💤 0 ❌
218 runs  218 ✅ 0 💤 0 ❌

Results for commit 5cedae9.

[github-actions]

Unit Tests Summary

  1 files   15 suites   1s ⏱️
163 tests 163 ✅ 0 💤 0 ❌
218 runs  218 ✅ 0 💤 0 ❌

Results for commit 5cedae9.

[llrs-roche]

Looks good. Nice addition of the renaming example, I had to double check the last example as I expected names(td) <- to work.