Describe HTML export in the change log file

[wolframroesler]

Add a line to the change log file that mentions the HTML Export feature.

Type of change

• ✅ Documentation (non-code change)

Description and Context

Fixes #3277 and #3311.

Screenshots

n/a

Testing strategy

n/a

Checklist:

• ✅ I have read the CONTRIBUTING document. [REQUIRED]
• ✅ My code follows the code style of this project. [REQUIRED]
• ✅ All new and existing tests passed. [REQUIRED]
• ✅ I have compiled and verified my code with -DWITH_ASAN=ON. [REQUIRED]
• ✅ My change requires a change to the documentation, and I have updated it accordingly.