docs: Update the README a little

Signed-off-by: Philip Withnall <withnall@endlessm.com>
10 jobs for project-docs in 19 minutes and 29 seconds (queued for 8 seconds)
Status Name Job ID Coverage
  Style Check
passed check-todos #1663536

00:01:15

passed style-check-diff #1663535

00:02:11

 
  Build
passed cross-android_api21_arm64 #1663539

00:01:22

passed cross-android_api28_arm64 #1663540

00:01:31

passed cross-mingw64 #1663541

00:02:16

passed debian-stable-x86_64 #1663538

00:02:22

passed fedora-x86_64 #1663537

00:09:00

passed msys2-mingw32 #1663542
win32-ps

00:09:28

passed vs2017-x64 #1663543
win32-ps

00:07:04

 
  Coverage
passed coverage #1663544

00:01:29

76.1%