feat(pyth-price-store): add readme (#2000)

* feat(pyth-price-store): add readme

* Update target_chains/solana/programs/pyth-price-store/README.md

Co-authored-by: Pavel Strakhov <ri@idzaaus.org>

---------

Co-authored-by: Pavel Strakhov <ri@idzaaus.org>

target_chains/solana/programs/pyth-price-store/README.md

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+# Pyth Price Store
+
+This program is designed to store Publisher's prices in a specific buffer per each publisher. Later, the prices from each publisher are retrieved in the
+Pythnet validator to calculate the aggregate price.
+
+## Build
+
+To build the program in a verifiable way, use [Solana Verify CLI](https://github.com/Ellipsis-Labs/solana-verifiable-build). This tool builds the program in
+a docker container to ensure that the resulting binary is deterministic and verifiable. Run the following command to build the program:
+
+```bash
+solana-verify build -- --features solana-program
+```
+
+Once the build is complete, the program binary will be located in the `target/deploy` directory.
+
+## Test
+
+Run `cargo test` to run the tests.