sui-graphql-client: update docs for using custom queries (#76)

crates/sui-graphql-client-build/README.md

@@ -2,22 +2,41 @@
 This crate provides a function to register a schema to enable building custom queries using cynic derive macros queries. Call
 this function in a `build.rs` file in your crate if you need to build custom queries.
 
-### Example
+### Usage
+1. Add this crate as a build dependency in your `Cargo.toml` file.
+```toml
+[build-dependencies]
+sui-graphql-client-build = { git = "https://github.com/mystenlabs/sui-rust-sdk", package = "sui-graphql-client-build", branch = "master" }
+```
+
+2. Add a `build.rs` file in your crate root directory and call the `register_schema` function in it.
 ```rust,ignore
 // build.rs file
 fn main() {
-    let schema_name = "MYSCHEMA"
+    let schema_name = "MYSCHEMA";
     sui_graphql_client_build::register_schema(schema_name);
 }
+```
 
-// Cargo.toml
-...
+3. Add the `cynic` and `sui-graphql-client` dependencies in your `Cargo.toml` file. You should have something like this.
+```toml
+# Cargo.toml
+# ...
 [dependencies]
 cynic = "3.8.0"
-...
+sui-graphql-client = { git = "https://github.com/mystenlabs/sui-rust-sdk", package = "sui-graphql-client", branch = "master" }
+
 [build-dependencies]
-sui_graphql_client_build = "VERSION_HERE"
+sui-graphql-client-build = { git = "https://github.com/mystenlabs/sui-rust-sdk", package = "sui-graphql-client-build", branch = "master" }
+```
 
+4. If using `cynic`, use the cynic generator to generate the Rust types from the GraphQL schema. \
+   Go to https://generator.cynic-rs.dev/ and paste the URL to the GraphQL service or manually copy paste the schema. \
+   Then you can select the fields in the query you want to have, and the generator will generate the Rust types for you.
+
+5. In your Rust code, you can now use the custom query types generated by `cynic`.
+
+```rust,ignore
 // lib.rs
 // Custom query
 use cynic::QueryBuilder;
@@ -37,3 +56,7 @@ async fn main() {
     println!("{:?}", q);
 }
 ```
+
+6. For `UInt53`, you can use `u64` type directly as the `sui-graphql-client`'s schema implements the `impl_scalar`. Similarly for other types (Base64, DateTime). See more available types here: https://github.com/MystenLabs/sui-rust-sdk/blob/02639f6b09375fe03fa2243868be17bec1dfa33c/crates/sui-graphql-client/src/query_types/mod.rs?plain=1#L124-L126
+
+7. Read the `cynic` [documentation](https://cynic-rs.dev/) to learn how to work with it, particularly when it comes to passing arguments to the query.