Merge pull request #133 from pohly/nil-logger

docs: describe handling of optional logger parameters

Author: thockin

logr.go

@@ -115,6 +115,15 @@ limitations under the License.
 // may be any Go value, but how the value is formatted is determined by the
 // LogSink implementation.
 //
+// Logger instances are meant to be passed around by value. Code that receives
+// such a value can call its methods without having to check whether the
+// instance is ready for use.
+//
+// Calling methods with the null logger (Logger{}) as instance will crash
+// because it has no LogSink. Therefore this null logger should never be passed
+// around. For cases where passing a logger is optional, a pointer to Logger
+// should be used.
+//
 // Key Naming Conventions
 //
 // Keys are not strictly required to conform to any specification or regex, but