How do the doppler effect explain why a sirens pitch increases as it approaches you?

You need to write a 1600 word essay about how to make a proper discord server, i will supply a outline that i have made. 1. make the server a. go create server b. make a name c. select a picture to use d. select your region e. press create 2. inviting people a. invite people you have on discord b. if no, copy link and add never expire c. optional to do later 3. make channels a. decide what you want this to be about "list options" b. make channels around your topic "one already made" c optional add voice chats "one already made" 4. make roles a. make roles for moderation "other roles for trusted people to you run server" b. optional make roles for other people "explain in essay" 5. make rules a. make rules for everyone to follow b. make rules for people higher in ranking to follow c. inform mods on how to enforce rules 6. optional add bots a. bots make life easy b. makes moderation easier to enforce 7. listen to community a. your community/people in your server are best to listen to "explain in essay" b. change things that your community wants to be modified. you need to go into detail about almost every line in order to reach the 1600 words.