doc(ant,maven): add labels for description

[vpa1977]

Ant and maven plugin descriptions are overriden by rockcraft. Add labels to simplify documentation override.

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[vpa1977]

Note: ruff shows the following error:

craft_parts/executor/environment.py:276:5: PLC0206 Extracting value from dictionary without calling `.items()`
    |
274 |       )
275 |   
276 |       for key in data:
    |  _____^
277 | |         if not skip or key not in skip:
278 | |             data[key] = _replace_attr(data[key], replacements)
    | |______________________________________________________________^ PLC0[20](https://github.com/canonical/craft-parts/actions/runs/12108844086/job/33757305803?pr=916#step:7:21)6
    |

Found 1 error.
make: *** [Makefile:91: test-ruff] Error 1

Probably due to mutating the dictionary while iterating through the keys.

[mr-cal]

Note: ruff shows the following error:

craft_parts/executor/environment.py:276:5: PLC0206 Extracting value from dictionary without calling `.items()`
    |
274 |       )
275 |   
276 |       for key in data:
    |  _____^
277 | |         if not skip or key not in skip:
278 | |             data[key] = _replace_attr(data[key], replacements)
    | |______________________________________________________________^ PLC0[20](https://github.com/canonical/craft-parts/actions/runs/12108844086/job/33757305803?pr=916#step:7:21)6
    |

Found 1 error.
make: *** [Makefile:91: test-ruff] Error 1

Probably due to mutating the dictionary while iterating through the keys.

Yep, I'll put up a PR to fix this unrelated failure whenever we come to an agreement in canonical/craft-application#580

[mr-cal]

Nevermind, Tiago already cleaned it up in https://github.com/canonical/craft-parts/pull/922/files

[tigarmo]

I'll update this branch and merge it once the linting fix is in main (later today)