Revert "Add auth sdk page (#108)" (#109)

This reverts commit a23bf93.

Author: leighmcculloch

docs/SDKs/rust-auth.mdx

@@ -29,8 +29,5 @@ Add the following sections to the `Cargo.toml` to import the `soroban-sdk`.
 testutils = ["soroban-sdk/testutils"]
 
 [dependencies]
-soroban-sdk = "0.0.4"
-
-[dev_dependencies]
-soroban-sdk = { version = "0.0.4", features = ["soroban-sdk/testutils"] }
+soroban-sdk = "0.0.3"
 ```