Clean up development documentation

Signed-off-by: 35V LG84 <35vlg84-x4e6b92@e257.fi>
2 jobs for master in 4 minutes and 41 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #149498253
test·jdk11

00:04:08

passed #149498254
test·jdk8

00:04:41

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