Update value and derivative deprecation message to make users aware of non-allocating batch evaluation

[termi-official]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.59%. Comparing base (b8f986a) to head (d4e36f7).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1125      +/-   ##
==========================================
+ Coverage   93.57%   93.59%   +0.01%     
==========================================
  Files          39       39              
  Lines        6073     6087      +14     
==========================================
+ Hits         5683     5697      +14     
  Misses        390      390              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[KnutAM]

LGTM
I don't think it is necessary to have the N and dNd\xi in green which simplifies a bit, but this will be removed after some time anyway (after a few releases I guess), so doesn't really matter much.

Realised that the function is not public, so let's discuss that before merging.