clarify license for vendored code (#5872)

mitmproxy/contrib/README

@@ -1,8 +0,0 @@
-
-Contribs:
-
-wbxml
-    - https://github.com/davidpshaw/PyWBXMLDecoder
-
-urwid
-    - Patches vendored from https://github.com/urwid/urwid/pull/448.

mitmproxy/contrib/README.md

@@ -0,0 +1,4 @@
+# mitmproxy/contrib 
+
+This directory includes vendored code from other sources.
+See the respective README and LICENSE files for details.

mitmproxy/contrib/click/LICENSE.BSD-3

@@ -0,0 +1,28 @@
+Copyright 2014 Pallets
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+1.  Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+2.  Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+
+3.  Neither the name of the copyright holder nor the names of its
+    contributors may be used to endorse or promote products derived from
+    this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

mitmproxy/contrib/kaitaistruct/LICENSE

@@ -0,0 +1 @@
+Either MIT or CC-0 - see the individual .ksy files for the respective license.

mitmproxy/contrib/kaitaistruct/README.md

@@ -0,0 +1,3 @@
+# Kaitai Struct Formats
+
+Most of the formats here are vendored from https://github.com/kaitai-io/kaitai_struct_formats/.

mitmproxy/contrib/kaitaistruct/dtls_client_hello.ksy

@@ -1,6 +1,7 @@
 meta:
   id: dtls_client_hello
   endian: be
+  license: MIT
 
 seq:
   - id: version