Fix typo in coding guidelines (#5363)

Signed-off-by: Stefan Triller <stefan.triller@telekom.de>

docs/documentation/development/guidelines.md

@@ -32,7 +32,7 @@ We are aware that these annotations can be used for **static** checks, but **not
 Thus for publicly exposed methods that belong to our API and are (potentially) called by external callers, we cannot omit a `null` check although a method parameter is marked to be not `null` via an annotation.
 We will get a warning in the IDE for this check, but we decided to live with that.
 For private methods or methods in an internal package we agreed to respect the annotations and omit an additional `null` check.  
-To use the annotaions, every bundle should have an **optional** `Import-Package` dependency to `org.eclipse.jdt.annotation`.
+To use the annotations, every bundle should have an **optional** `Import-Package` dependency to `org.eclipse.jdt.annotation`.
 Classes should be annotated by `@NonNullByDefault` and return types, parameter types, generic types etc. are annotated with `@Nullable` only.
 Fields that get a static and mandatory reference injected through OSGi Declarative Services can be annotated with