Add efcore as project-specific tool; update documentation

.config/dotnet-tools.json

@@ -0,0 +1,12 @@
+{
+  "version": 1,
+  "isRoot": true,
+  "tools": {
+    "dotnet-ef": {
+      "version": "8.0.4",
+      "commands": [
+        "dotnet-ef"
+      ]
+    }
+  }
+}

Readme.md

@@ -9,9 +9,8 @@ An automated way to recognize birthdays in your community!
 
 #### Running your own instance
 You need:
-* .NET 6 (https://dotnet.microsoft.com/en-us/)
+* .NET 8 (https://dotnet.microsoft.com/en-us/)
 * PostgreSQL (https://www.postgresql.org/)
-* EF Core tools (https://learn.microsoft.com/en-us/ef/core/get-started/overview/install#get-the-entity-framework-core-tools)
 * A Discord bot token (https://discord.com/developers/applications)
 
 Get your bot token and set up your database user and schema, then create a JSON file containing the following:
@@ -28,10 +27,11 @@ Get your bot token and set up your database user and schema, then create a JSON
 Then run the following commands:
 ```sh
 $ dotnet restore
+$ dotnet tool restore
 $ dotnet ef database update -- -c path/to/config.json
 ```
 
 And finally, to run the bot:
-```
+```sh
 $ dotnet run -c Release -- -c path/to/config.json
 ```