Merge pull request #7297 from electron/clean-docs

Mention build cleaning on all three platforms

docs/development/build-instructions-linux.md

@@ -105,7 +105,7 @@ After building is done, you can find the `electron` debug binary under `out/D`.
 To clean the build files:
 
 ```bash
-$ ./script/clean.py
+$ npm run clean
 ```
 
 ## Troubleshooting

docs/development/build-instructions-osx.md

@@ -51,6 +51,14 @@ After building is done, you can find `Electron.app` under `out/D`.
 Electron can only be built for a 64bit target on macOS and there is no plan to
 support 32bit macOS in the future.
 
+## Cleaning
+
+To clean the build files:
+
+```bash
+$ npm run clean
+```
+
 ## Tests
 
 Test your changes conform to the project coding style using:

docs/development/build-instructions-windows.md

@@ -77,6 +77,14 @@ To generate a Visual Studio project, you can pass the `--msvs` parameter:
 $ python script\bootstrap.py --msvs
 ```
 
+## Cleaning
+
+To clean the build files:
+
+```powershell
+$ npm run clean
+```
+
 ## Tests
 
 Test your changes conform to the project coding style using: