Rename lesson files to preserve ordering?

[markerikson]

The first 9 lessons currently only use one digit for their numbering, so the filenames are not sorted numerically as a result:

0-object-elements.html
1-element-factory.html
10-example-app.html
...
16-advanced-integration.html
2-jsx.html
3-nested-elements.html

Might be nice to give them two-digit numbers so everything sorts cleanly: 01, 02, 03, ... 10, 11, 12

[kay-is]

Good idea, thank you :)