refactor: Format files using Prettier

Actual command: `nix-shell --packages nodePackages.prettier --pure --run
'prettier --write .'`.

README.md

@@ -33,11 +33,11 @@ jobs:
   tests:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
-    - uses: cachix/install-nix-action@v22
-      with:
-        nix_path: nixpkgs=channel:nixos-unstable
-    - run: nix-build
+      - uses: actions/checkout@v3
+      - uses: cachix/install-nix-action@v22
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - run: nix-build
 ```
 
 ## Usage with Flakes
@@ -51,12 +51,12 @@ jobs:
   tests:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
-    - uses: cachix/install-nix-action@v22
-      with:
-        github_access_token: ${{ secrets.GITHUB_TOKEN }}
-    - run: nix build
-    - run: nix flake check
+      - uses: actions/checkout@v3
+      - uses: cachix/install-nix-action@v22
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      - run: nix build
+      - run: nix flake check
 ```
 
 To install Nix from any commit, go to [the corresponding installer_test action](https://github.com/NixOS/nix/runs/2219534360) and click on "Run cachix/install-nix-action@XX" step and expand the first line.