README: Fix spelling error

Signed-off-by: Vasilis Tsiligiannis <[email protected]>
4 jobs for master in 26 minutes and 48 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Style
passed #648012014
style

00:00:22

 
  Test
passed #648012015
test

00:11:39

 
  Build
passed #648012016
debian

00:10:05

 
  Deploy
passed #648012017
deploy

00:04:40