added arch document

x/oracle/docs/arch.md

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+# Description
+
+The feeder and processor in the oracle runs as a Cosmos module that encompasses both functions.
+
+### Feeder
+
+A feeder is responsible to fetch the data from remote sources and send the resulting data to the processor
+
+### Processor
+
+A processor is responsible for combining and filtering votes to produce a single value that it writes to the DB.
+
+# Oracle flow
+
+### Feeders
+
+* Feeders start and read their configuration from the CRUD module
+
+* Feeders then request information from the sources provided in the configuration
+
+* For each source a preflight vote proof is generated and put on the blockchain
+
+  The preflight consists of the vote hashed with the address of the validator (to prevent free-riders)
+
+* For each source at 20 seconds past the minute a vote is cast on the blockchain that matches the value in the preflight proof
+
+### Processors
+
+* Listens for preflight proofs and votes on the blockchain
+* When a vote is received it is compared with the preflight proof - if the proof does not match, the vote is discarded
+* votes are then compared and combined using a combination of weights and elimination rules
+* A single value is written to the DB for each source along with the votes that led to the single value
+
+