doc/apps: Add BARE

Documentation/applications/netutils/bare/index.rst

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+===========================================
+``bare`` Binary Application Record Encoding
+===========================================
+
+BARE is a simple binary representation for structured application data, see
+https://baremessages.org/.
+
+BARE implementation ported to NuttX is ``cbare``, see
+https://git.sr.ht/~fsx/cbare.
+
+BARE_ is similar to other binary formats like CBOR_, BSON_, or `Protocol
+Buffers`_.
+
+.. _BARE: https://baremessages.org/
+.. _CBOR: https://cbor.io/
+.. _BSON: https://bsonspec.org/
+.. _Protocol Buffers: https://protobuf.dev/
+
+BARE at glance, from its web page:
+
+- Messages are encoded in binary and compact in size. Messages do not contain
+  schema information — they are not self-describing.
+
+- BARE is optimized for small messages. It is not optimized for encoding large
+  amounts of data in a single message, or efficiently reading a message with
+  fields of a fixed size. However, all types are aligned to 8 bits, which does
+  exchange some space for simplicity.
+
+- BARE's approach to extensibility is conservative: messages encoded today will
+  be decodable tomorrow, and vice-versa. But extensibility is still possible;
+  implementations can choose to decode user-defined types at a higher level and
+  map them onto arbitrary data types.
+
+- The specification is likewise conservative. Simple implementations of message
+  decoders and encoders can be written inside of an afternoon.
+
+- An optional DSL is provided to document message schemas and provide a source
+  for code generation. However, if you prefer, you may also define your schema
+  using the type system already available in your programming language.