Docs: Fix tutorial "shear"

[adtzlr]

fixes #234

also removes offsets arguments from tools.force() and tools.moment() and use field.offsets instead.

[codecov-commenter]

Codecov Report

Merging #235 (7e36c4b) into main (0dea8b9) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 7e36c4b differs from pull request most recent head 442bfea. Consider uploading reports for the commit 442bfea to get more accurate results

@@           Coverage Diff           @@
##             main     #235   +/-   ##
=======================================
  Coverage   96.61%   96.61%           
=======================================
  Files          66       66           
  Lines        2774     2774           
=======================================
  Hits         2680     2680           
  Misses         94       94           

Impacted Files	Coverage Δ
felupe/tools/_post.py	100.00% <100.00%> (ø)

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