Fix list item numbering in substreams page (#800)

website/pages/en/substreams.mdx

@@ -14,17 +14,17 @@ Substreams is a powerful blockchain indexing technology designed to enhance perf
 
 1. **You write a Rust program, which defines the transformations that you want to apply to the blockchain data.** For example, the following Rust function extracts relevant information from an Ethereum block (number, hash, and parent hash).
 
-```rust
-fn get_my_block(blk: Block) -> Result<MyBlock, substreams::errors::Error> {
-    let header = blk.header.as_ref().unwrap();
-
-    Ok(MyBlock {
-        number: blk.number,
-        hash: Hex::encode(&blk.hash),
-        parent_hash: Hex::encode(&header.parent_hash),
-    })
-}
-```
+   ```rust
+   fn get_my_block(blk: Block) -> Result<MyBlock, substreams::errors::Error> {
+       let header = blk.header.as_ref().unwrap();
+
+       Ok(MyBlock {
+           number: blk.number,
+           hash: Hex::encode(&blk.hash),
+           parent_hash: Hex::encode(&header.parent_hash),
+       })
+   }
+   ```
 
 2. **You wrap up your Rust program into a WASM module just by running a single CLI command.**