docs: add trademark non-affiliation notice (README + NOTICE)

Add a Trademarks & disclaimer section to the README and a root NOTICE
file stating this is an independent, unofficial project not affiliated
with Samsung, and that Samsung/SmartThings marks are used nominatively.

Ship NOTICE inside the distributed artifacts by adding it to
license-files (wheel .dist-info/licenses/) and the sdist include list.

pyproject.toml

@@ -9,7 +9,7 @@ description = "Local CoAP-over-DTLS (OCF) transport + polling layer for Samsung
 readme = "README.md"
 requires-python = ">=3.11"
 license = "MIT"
-license-files = ["LICENSE"]
+license-files = ["LICENSE", "NOTICE"]
 authors = [{ name = "Jack Nagy" }]
 keywords = ["smartthings", "samsung", "ocf", "coap", "dtls", "home-assistant", "iot"]
 classifiers = [
@@ -60,5 +60,6 @@ include = [
     "tests",
     "README.md",
     "LICENSE",
+    "NOTICE",
     "pyproject.toml",
 ]