Fix extra text block colons.

[alarshi]

I came across a small typo in the documentation (see below), this PR fixes it :)

main:

this branch:

[alarshi]

Ah, yes. I keep forgetting it. Thank you for the review! :) I also realized that the issue was the incorrect rendering of the warning block above in Filter output. I fixed it in the last commit and the output should look like the image below:

[gassmoeller]

/rebuild