fix: user registration menu name

[dpgaspar]

Description

Small fix for an old copy pasta mistake

ADDITIONAL INFORMATION

• Has associated issue:
• Is CRUD MVC related.
• Is Auth, RBAC security related.
• Changes the security db schema.
• Introduces new feature
• Removes existing feature

[codecov]

Codecov Report

Merging #2051 (d155f9b) into master (ae25ad4) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2051   +/-   ##
=======================================
  Coverage   78.62%   78.62%           
=======================================
  Files          72       72           
  Lines        8698     8698           
=======================================
  Hits         6839     6839           
  Misses       1859     1859           

Flag	Coverage Δ
python	78.62% <100.00%> (ø)

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Impacted Files	Coverage Δ
flask_appbuilder/security/manager.py	76.16% <ø> (ø)
flask_appbuilder/__init__.py	100.00% <100.00%> (ø)