If you've been given this link to follow, it's probably because you've posted a response message on Slack without putting it in the relevant thread.
Messages on Slack which are responses to an earlier message should all be in the thread of the original.
Why does this matter?
This might not seem important to you but it is important to the volunteers.
For those users who are following many channels (e.g. teachers) it is difficult for them to find important messages if the channels are very "noisy" - so they are less likely to be able to respond to important trainee questions.
If the messages are all in their correct threads, it is easier for the teachers to scan through the topics to see what is important.
Help the other users - reply in threads to keep Slack tidy.
What should I do?
To tidy up the issue, it is normally good to:
re-post your message in the correct thread
delete your message from the channel
However, don't do this if people have since replied in the thread of your message and created an important conversation.