Fix error message when checking literalinclude in docs (#11140)
Fix error message when checking literalinclude in docs (#11140)

Before:
```
literalinclude directive is is prohibited for example DAGs
```

After:

```
literalinclude directive is prohibited for example DAGs
```
lyft/incubator-airflow,apache/airflow,airbnb/airflow,apache/incubator-airflow,Acehaidrey/incubator-airflow,mrkm4ntr/incubator-airflow,nathanielvarona/airflow,lyft/incubator-airflow,dhuang/incubator-airflow,apache/incubator-airflow,mistercrunch/airflow,apache/incubator-airflow,apache/airflow,DinoCow/airflow,lyft/incubator-airflow,danielvdende/incubator-airflow,apache/airflow,danielvdende/incubator-airflow,nathanielvarona/airflow,DinoCow/airflow,DinoCow/airflow,bolkedebruin/airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow,dhuang/incubator-airflow,sekikn/incubator-airflow,Acehaidrey/incubator-airflow,apache/airflow,sekikn/incubator-airflow,airbnb/airflow,danielvdende/incubator-airflow,mistercrunch/airflow,danielvdende/incubator-airflow,Acehaidrey/incubator-airflow,bolkedebruin/airflow,apache/incubator-airflow,bolkedebruin/airflow,Acehaidrey/incubator-airflow,DinoCow/airflow,lyft/incubator-airflow,sekikn/incubator-airflow,bolkedebruin/airflow,bolkedebruin/airflow,mistercrunch/airflow,mrkm4ntr/incubator-airflow,mistercrunch/airflow,danielvdende/incubator-airflow,dhuang/incubator-airflow,mrkm4ntr/incubator-airflow,airbnb/airflow,sekikn/incubator-airflow,apache/airflow,nathanielvarona/airflow,cfei18/incubator-airflow,cfei18/incubator-airflow,nathanielvarona/airflow,nathanielvarona/airflow,cfei18/incubator-airflow,dhuang/incubator-airflow,mrkm4ntr/incubator-airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,apache/airflow,cfei18/incubator-airflow,airbnb/airflow