nitpick: rename examples from program.rl to program.c.rl

so the file extension shows the embedded language

each compile step removes one extension

```
ragel atoi.c.rl -o atoi.c
gcc atoi.c -o atoi
```

```
atoi.c.rl
atoi.c
atoi
```

or

```
atoi.go.rl
atoi.go
atoi
```
