Fix Vala compiler links so that they don't use file extensions

Author: colinkiama

docs/contributor-guide/compiler-guide/03-00-the-vala-compiler.md

@@ -3,10 +3,10 @@
 I suppose the best place to start is valac, the tool which Vala
 programmers know the best.
 
-#### [3.1. Vala in a Nutshell](03-00-the-vala-compiler/03-01-vala-in-a-nutshell.md)
-#### [3.2. Parser](03-00-the-vala-compiler/03-02-parser.md)
-#### [3.3. Semantic Analyzer](03-00-the-vala-compiler/03-03-semantic-analyzer.md)
-#### [3.4. Symbol Resolution](03-00-the-vala-compiler/03-04-symbol-resolution.md)
-#### [3.5. Flow Analyzer](03-00-the-vala-compiler/03-05-flow-analyzer.md)
-#### [3.6. C Code Generation](03-00-the-vala-compiler/03-06-c-code-generation.md)
-#### [3.7. C Code Compilation and Linking](03-00-the-vala-compiler/03-07-c-code-compilation-and-linking.md)
+#### [3.1. Vala in a Nutshell](03-00-the-vala-compiler/03-01-vala-in-a-nutshell)
+#### [3.2. Parser](03-00-the-vala-compiler/03-02-parser)
+#### [3.3. Semantic Analyzer](03-00-the-vala-compiler/03-03-semantic-analyzer)
+#### [3.4. Symbol Resolution](03-00-the-vala-compiler/03-04-symbol-resolution)
+#### [3.5. Flow Analyzer](03-00-the-vala-compiler/03-05-flow-analyzer)
+#### [3.6. C Code Generation](03-00-the-vala-compiler/03-06-c-code-generation)
+#### [3.7. C Code Compilation and Linking](03-00-the-vala-compiler/03-07-c-code-compilation-and-linking)