doc: Tell about HdyLeaflet transition-type changes

We don't want to surprize our users when they'll migrate to 1.0.
11 jobs for api-1-leaflet-default in 20 minutes and 59 seconds (queued for 30 minutes and 5 seconds)
Status Job ID Name Coverage
  Build
passed #246391
librem5
api-visibility

00:02:28

passed #246393
librem5
build-debian-clang

00:03:25

passed #246392
librem5
build-debian-gcc

00:02:41

passed #246394
librem5
build-fedora-gcc

00:02:59

 
  Test+Docs
passed #246395
librem5
build-gtkdoc

00:02:25

passed #246396
librem5
unit-test

00:02:29

43.6%
 
  Package
passed #246397
librem5
package-debian-buster

00:02:50

passed #246398
librem5:arm64
package-debian-buster:arm64

00:06:28

failed #246399
flatpak allowed to fail
package-flatpak

00:00:50

 
  Test Package
passed #246400
librem5
autopkgtest-debian-buster-package

00:02:35

passed #246401
librem5
lintian-debian-buster-package

00:00:54

 
Name Stage Failure
failed
package-flatpak Package
Committing stage finish to cache
Exporting sm.puri.Handy.Demo to repo
error: Writing content object: min-free-space-percent '3%' would be exceeded, at least 4.1?kB requested
Export failed: Child process exited with code 1
Uploading artifacts...
_build/meson-logs/meson-log.txt: found 1 matching files
WARNING: sm.puri.Handy.Demo-dev.flatpak: no matching files
Uploading artifacts to coordinator... ok
id=246399 responseStatus=201 Created token=VUGgpjtn
ERROR: Job failed: exit code 1