Fix relative links in markdown

CONTRIBUTING.md

@@ -1,6 +1,6 @@
 # Development process
 
-Please read the Working Process/Quickstart Guide in [[README.md]] first.
+Please read the Working Process/Quickstart Guide in [README.md](README.md) first.
 
 For any modification of the observatory-extension, such as adding new features,
 refactoring or bug-fixing, a topic branch must be created out of the `develop`

README.md

@@ -44,7 +44,7 @@ and developers must not commit or merge into it.
 ## Development Guidelines
 
 For a detailed description of the development process please see
-the [[CONTRIBUTING.md]] guide.
+the [CONTRIBUTING.md](CONTRIBUTING.md) guide.
 
 Any modification to the source code
 shall always be done in a topic branch created from the `develop` branch.
@@ -60,5 +60,5 @@ make test
 ## Release
 
 The release and deployment process is described in the
-[[RELEASE.md]] guide and it is the responsibility of the designated
+[RELEASE.md](RELEASE.md) guide and it is the responsibility of the designated
 release manager.

RELEASE.md

@@ -1,7 +1,7 @@
 # Release & Deployment Process
 
-Please read the Working Process/Quickstart Guide in [README.md]]
-and the Development guidelines in [[CONTRIBUTING.md]].
+Please read the Working Process/Quickstart Guide in [README.md](README.md)
+and the Development guidelines in [CONTRIBUTING.md](CONTRIBUTING.md).
 
 The release process of a new version of the extension
 shall be performed by the designated *Release Manager*.