docs: add details on locating proxies.xml examples and clarify conf… (#2389)

* docs: add details on locating `proxies.xml` examples and clarify configuration transition from XML to YAML

* docs: improve `proxies.xml` README formatting and update GitHub link description

Author: predic8

distribution/examples/proxies.xml.README.md

@@ -0,0 +1,10 @@
+# Where can I find proxies.xml samples?
+
+Membrane is moving from XML-based configuration to YAML-based configuration. However, Membrane still
+supports the XML-based configuration with 'proxies.xml' files. Some examples in the subfolders are
+using the YAML and some are using the XML configuration.
+
+You can find the 'proxies.xml' files at the github repository:
+
+https://github.com/membrane/api-gateway/tree/master/distribution/examples
+