cleanup documentation (#281)

Author: hohwille

documentation/_Sidebar.asciidoc

@@ -49,6 +49,7 @@
 === Coding 
 * link:coding-conventions.asciidoc[Coding Conventions]
 * link:coding-tools.asciidoc[Development Tools]
+* https://github.com/devonfw/.github/blob/master/CONTRIBUTING.asciidoc#contributing[Contributing to devonfw]
 
 === Tutorials
 * link:tutorial-newapp.asciidoc[Start a new application]

documentation/devonfw-code-contribution.asciidoc

@@ -103,7 +103,7 @@ Example:
  [D: 2013-09-05 16:40:36,464] [P: DEBUG] [C: 12345] [T: main] [L: my.package.MyClass]-[M: My message...]
 
 == Security
-In order to prevent https://www.owasp.org/index.php/Log_Forging[log forging] attacks we provide a special appender for logback in link:guide-logging.asciidoc[devonfw-logging]. If you use it (see xref:configuration[]) you are safe from such attacks.
+In order to prevent https://www.owasp.org/index.php/Log_Forging[log forging] attacks we provide a special appender for logback in devon4j-logging. If you use it (see xref:configuration[]) you are safe from such attacks.
 
 == Correlation ID
 In order to correlate separate HTTP requests to services belonging to the same user / session, we provide a servlet filter called `DiagnosticContextFilter`. This filter takes a provided correlation ID from the HTTP header `X-Correlation-Id`. If none was found, it will generate a new correlation id as `UUID`. This correlation ID is added as MDC to the logger. Therefore, it will then be included to any log message of the current request (thread). Further concepts such as link:guide-service-client.asciidoc[service invocations] will pass this correlation ID to subsequent calls in the application landscape. Hence you can find all log messages related to an initial request simply via the correlation ID even in highly distributed systems.
@@ -141,4 +141,4 @@ This will produce something like:
   "level":"INFO",
   "level_value":20000,
   "appname":"basic",}
-----
+----