This commit updates the docs examples to be compatible with the
`variable-name` tslint rule without requiring the
`allow-leading-underscore` and `allow-trailing-underscore` options.
This is in preparation of updating the docs examples `tslint.json` to
match the one generated for new Angular CLI apps in a future commit.
PR Close#38143
JiaLiPassion
George Kalpakas
Tim Deschryver
Carlos Ortiz García
Judy Bogart