Remove old files (#3077)

from https://github.com/woodpecker-ci/woodpecker/pull/3069

- `.changelog.yml`: no longer used
- `pipeline/samples`

docs/.prettierrc.js

@@ -1,8 +0,0 @@
-module.exports = {
-  semi: true,
-  trailingComma: 'all',
-  singleQuote: true,
-  printWidth: 120,
-  tabWidth: 2,
-  endOfLine: 'lf',
-};