Minor change in the README.

README.md

@@ -48,7 +48,7 @@ end
 
 We now have our collection of documents to index!
 
-## The `ColBERTConfig`
+### The `ColBERTConfig`
 
 The next step is to create a configuration object containing details about all parameters used during indexing/searching using ColBERT. All this information is contained in a type called `ColBERTConfig`. Creating a `ColBERTConfig` is easy; it has the right defaults for most users, and one can change the settings using simple kwargs. In this example, we'll create a config for the collection `1kcollection.txt` we just created, and we'll also use [`CUDA.jl`](https://github.com/JuliaGPU/CUDA.jl) for GPU support (you can use any GPU backend supported by [Flux.jl](https://github.com/FluxML/Flux.jl))!