publish libraries to avoid users to have to download them one by one

lib/esp8266_mdns/library.properties

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+name=esp8266_mdns
+version=1.1.7
+author=mrdunk
+maintainer=mrdunk
+sentence=mDNS queries and responses on esp8266.
+paragraph=Or to describe it another way: An mDNS Client or Bonjour Client library for the esp8266.
+category=Communication
+url=https://github.com/mrdunk/esp8266_mdns
+architectures=esp8266