readme: remove trailing whitespaces

Link: nix-community#132

Author: trueNAHO

README.md

@@ -31,7 +31,7 @@ Include the nixos module in your configuration:
 {
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable-small";
-  
+
     nix-index-database.url = "github:nix-community/nix-index-database";
     nix-index-database.inputs.nixpkgs.follows = "nixpkgs";
   };
@@ -100,7 +100,7 @@ You can then call `nix-locate` as usual, it will automatically use the database
       url = "github:nix-community/home-manager";
       inputs.nixpkgs.follows = "nixpkgs";
     };
-    
+
     nix-index-database.url = "github:nix-community/nix-index-database";
     nix-index-database.inputs.nixpkgs.follows = "nixpkgs";
   };