Merge pull request #75 from ethouris/extra-doc

Added some extra info to contributing guide

CONTRIBUTING.md

@@ -12,7 +12,14 @@ Comment on any GitHub issue, open or closed. The only guidelines here are to be
 
 ## Pull Requests
 
-Submit a pull request at any time, whether an issue has been created or not. It may be helpful to discuss your goals in an issue first, though many things can best be shown with code.
+Submit a pull request at any time, whether an issue has been created or not. It may be helpful to discuss your goals in an issue first, though many things can best be shown with code. Also do not hesitate to ask other users for opinion and discuss the ideas using the ticketing system before you start making your changes. This is especially important in these areas:
+
+* the build system and its variables
+* the SRT library public API
+* command line tools and their call syntax
+* the reusable parts (such as utilities)
+* SRT protocol definitions
+* portability and platform-specific parts
 
 ## Code Style
 
@@ -46,4 +53,4 @@ By making a contribution to this project, I certify that:
   are public and that a record of the contribution (including all
   personal information I submit with it, including my sign-off) is
   maintained indefinitely and may be redistributed consistent with
-  this project or the open source license(s) involved.
+  this project or the open source license(s) involved.