docs: fix typo in codegen indexer command (#83)

documentation/docs/pages/docs/start-building/rust-project-deep-dive/indexers.mdx

@@ -21,7 +21,7 @@ This will overwrite any custom logic you have written in the indexers folder so
 :::
 
 ```bash
-rindexer codegen indexers
+rindexer codegen indexer
 ```
 
 To help understand the interfaces and ways rindexer handlers can be extended we will look at an example.
@@ -1006,4 +1006,4 @@ cargo run -- --graphql
 
 When you start changing your YAML configuration file and regenerating your typings the indexer functions may break or need editing
 to match the new typings. You can regenerate the indexers folder but this will overwrite any changes you did.
-Luckily the rust compiler is very good at telling you what you need to change.
+Luckily the rust compiler is very good at telling you what you need to change.