more compact chktex output

Author: dpo

.github/workflows/lint.yml

@@ -24,7 +24,7 @@ jobs:
         result-encoding: string
         script: |
           const fs = require('fs');
-          return "Chktex output: \n```\n" + fs.readFileSync("${{ github.workspace }}/chktex_output.txt", "utf8").toString() + "```";
+          return "<details>\n<summary>Chktex output</summary>\n\n```\n" + fs.readFileSync("${{ github.workspace }}/chktex_output.txt", "utf8").toString() + "\n```\n</details>";
     - name: Comment in PR
       uses: thollander/actions-comment-pull-request@v2
       with: