titlebar: Fix a mention of HdyLeaflet in the docs

3 jobs for titlebar-doc in 4 minutes and 12 seconds
Status Job ID Name Coverage
  Build
passed #3866
librem5
build-debian-clang

00:04:12

passed #3865
librem5
build-debian-gcc

00:03:42

24.8%
passed #3867
librem5
build-debian-package

00:03:48