Header line: Fixing up spelling mistakes within the VTR documentation

THe words 'Navigate' and 'messages' were spelled incorrectly and they
were found within the 'Commit Procedures' and 'Commit Messages and
Structure' sections of the documentation. The words were replaced with
the correct spelling.

Author: Srivat97

README.developers.md

@@ -72,7 +72,7 @@ The overall approach is similar, but we call out the differences below.
 
 8. Create a Pull Request (PR) to request your changes be merged into VTR.
 
-    * Navitage to your branch on GitHub
+    * Navigate to your branch on GitHub
 
         a. **External Developers**
 
@@ -92,7 +92,7 @@ The overall approach is similar, but we call out the differences below.
 
 ## Commit Messages
 
-Commit messagaes are an important part of understanding the code base and it's history.
+Commit messages are an important part of understanding the code base and it's history.
 It is therefore *extremely* important to provide the following information in the commit message:
 
 * What is being changed?