chore: switch from yarn to npm

We normally use yarn, but as this project is becoming more popular, it seems like an unwarranted extra step for people to get the right version of yarn.

.github/workflows/release.yml

@@ -16,9 +16,9 @@ jobs:
         with:
           node-version: lts/*
       - name: Install dependencies
-        run: yarn
+        run: npm install
       - name: Build
-        run: yarn build
+        run: npm run build
       - name: Release
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -4,5 +4,4 @@ sample_img/
 i18n/
 node_modules/
 version.json
-docs/
-yarn-error.log
+docs/

docu-notion.config.ts

@@ -1,5 +1,5 @@
 /* This file is only used when testing docu-notion itself, not when it is used as a library.
-  E.g., if you run `yarn pull-test-tagged`, docu-notion will read this file and use it to configure itself,
+  E.g., if you run `npm run pull-test-tagged`, docu-notion will read this file and use it to configure itself,
   using these example plugins.
  */