Dynamically insert help categories into DORMANT_MSG
As [suggested by Lemon](https://discord.com/channels/267624335836053506/429409067623251969/874919321283993631) in #community-meta, this will insert the correct category names into the DORMANT_MSG that's sent when a channel is moved to the dormant category.
diff --git a/bot/exts/help_channels/_cog.py b/bot/exts/help_channels/_cog.py
index 35658d11..afaf9b0b 100644
--- a/bot/exts/help_channels/_cog.py
+++ b/bot/exts/help_channels/_cog.py
@@ -387,7 +387,15 @@ class HelpChannels(commands.Cog):
         )
 
         log.trace(f"Sending dormant message for #{channel} ({channel.id}).")
-        embed = discord.Embed(description=_message.DORMANT_MSG)
+        dormant_category = await channel_utils.try_get_channel(constants.Categories.help_dormant)
+        available_category = await channel_utils.try_get_channel(constants.Categories.help_available)
+        embed = discord.Embed(
+            description=_message.DORMANT_MSG.format(
+                dormant=dormant_category.name,
+                available=available_category.name,
+                asking_guide=_message.ASKING_GUIDE_URL
+            )
+        )
         await channel.send(embed=embed)
 
         log.trace(f"Pushing #{channel} ({channel.id}) into the channel queue.")
diff --git a/bot/exts/help_channels/_message.py b/bot/exts/help_channels/_message.py
index befacd26..cf070be8 100644
--- a/bot/exts/help_channels/_message.py
+++ b/bot/exts/help_channels/_message.py
@@ -29,15 +29,15 @@ AVAILABLE_TITLE = "Available help channel"
 
 AVAILABLE_FOOTER = "Closes after a period of inactivity, or when you send !close."
 
-DORMANT_MSG = f"""
-This help channel has been marked as **dormant**, and has been moved into the **Help: Dormant** \\
+DORMANT_MSG = """
+This help channel has been marked as **dormant**, and has been moved into the **{dormant}** \\
 category at the bottom of the channel list. It is no longer possible to send messages in this \\
 channel until it becomes available again.
 
 If your question wasn't answered yet, you can claim a new help channel from the \\
-**Help: Available** category by simply asking your question again. Consider rephrasing the \\
+**{available}** category by simply asking your question again. Consider rephrasing the \\
 question to maximize your chance of getting a good answer. If you're not sure how, have a look \\
-through our guide for **[asking a good question]({ASKING_GUIDE_URL})**.
+through our guide for **[asking a good question]({asking_guide})**.
 """
 
 
['bot/exts/help_channels/_message.py', 'bot/exts/help_channels/_cog.py']