Add test to check whether all DSL keywords appear in the manual

[racke]

The following keywords are missing according to this test:

not ok 3 - Checking for keyword app
not ok 9 - Checking for keyword context
not ok 13 - Checking for keyword dancer_app
not ok 14 - Checking for keyword dancer_major_version
not ok 19 - Checking for keyword delayed
not ok 21 - Checking for keyword done
not ok 22 - Checking for keyword dsl
not ok 27 - Checking for keyword flush
not ok 34 - Checking for keyword header
not ok 35 - Checking for keyword headers
not ok 38 - Checking for keyword log
not ok 50 - Checking for keyword push_header
not ok 57 - Checking for keyword response
not ok 61 - Checking for keyword runner

[cromedome]

Nice test! :+1: I'll have to write some docs before the next release! 😄

[cromedome]

Incorporated into #1609. Closing. Thank you!