doc: add price data feed overview

[codecov-commenter]

Codecov Report

Merging #409 (13e6ec1) into develop (94a3960) will increase coverage by 3.46%. The diff coverage is n/a.

:exclamation: Current head 13e6ec1 differs from pull request most recent head 6d09c4a. Consider uploading reports for the commit 6d09c4a to get more accurate results

@@             Coverage Diff             @@
##           develop     #409      +/-   ##
===========================================
+ Coverage    71.32%   74.78%   +3.46%     
===========================================
  Files           68       56      -12     
  Lines         2326     1995     -331     
  Branches       351      297      -54     
===========================================
- Hits          1659     1492     -167     
+ Misses         667      503     -164     

Flag	Coverage Δ
batch-submitter	62.18% <ø> (ø)
contracts	87.18% <ø> (ø)
core-utils	53.79% <ø> (ø)
data-transport-layer	?
message-relayer	?

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Impacted Files	Coverage Δ
...kages/data-transport-layer/src/utils/validation.ts
...ices/l1-ingestion/handlers/state-batch-appended.ts
packages/message-relayer/hardhat.config.ts
...layer/src/services/l1-ingestion/handlers/errors.ts
packages/data-transport-layer/src/utils/common.ts
...ckages/data-transport-layer/src/utils/contracts.ts
packages/data-transport-layer/src/utils/eth-tx.ts
...ices/l1-ingestion/handlers/transaction-enqueued.ts
.../l1-ingestion/handlers/sequencer-batch-appended.ts
packages/message-relayer/src/relay-tx.ts
... and 2 more

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