Use round parentheses instead of square brackets in link destinations

Markdown syntax tweak

training/index.md

@@ -21,13 +21,13 @@ sure we're all doing it consistently.
 ## Introduction Index
 This is a list of all the documents in this series. Start at the top and work your way down.
 
-1. [What's Charcoal?][/training/charcoal]
-2. [What's spam?][/training/spam]
-3. [When do you watch spam?][/training/watch]
-4. [Privileges][/training/privileges]
-5. [Handling reports][/training/reports]
-6. [Autoflagging][/training/autoflagging]
-7. [Further privileges: Core][/training/core]
-8. [Further privileges: Blacklister][/training/blacklister]
+1. [What's Charcoal?](/training/charcoal)
+2. [What's spam?](/training/spam)
+3. [When do you watch spam?](/training/watch)
+4. [Privileges](/training/privileges)
+5. [Handling reports](/training/reports)
+6. [Autoflagging](/training/autoflagging)
+7. [Further privileges: Core](/training/core)
+8. [Further privileges: Blacklister](/training/blacklister)
 
 [hq]: https://chat.stackexchange.com/rooms/11540/charcoal-hq