Fix typo in changelog

Author: jorgensd

Changelog.md

@@ -50,7 +50,7 @@
 - API updates wrt. DOLFINx. `Form`->`form`, `DirichletBC`->`dirichletbc`.
 - Updates on error computations in [Error control: Computing convergence rates](chapter4/convergence).
 - Added tutorial on interpolation of `ufl.Expression` in [Deflection of a membrane](chapter1/membrane_code).
-- Added tutorial on how to apply constant-valued Dirichet conditions in [Deflection of a membrane](chapter1/membrane_code).
+- Added tutorial on how to apply constant-valued Dirichlet conditions in [Deflection of a membrane](chapter1/membrane_code).
 - Various API changes relating to the import structure of DOLFINx
 
 ## 0.3.0 (09.09.2021)