Fix medical qualification success message

[zhacatomn]

Changes

• Now, upon a successful volunteer add/edit, the medical tags will now show the "qualification level", and will be a comma delimited string

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.01 :tada:

Comparison is base (f2d473d) 75.27% compared to head (713c85a) 75.29%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #280 +/- ## ============================================ + Coverage 75.27% 75.29% +0.01% Complexity 1129 1129 ============================================ Files 139 139 Lines 3353 3355 +2 Branches 371 371 ============================================ + Hits 2524 2526 +2 Misses 701 701 Partials 128 128 ``` | [Impacted Files](https://codecov.io/gh/AY2223S2-CS2103T-W12-1/tp/pull/280?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AY2223S2-CS2103T-W12-1) | Coverage Δ | | |---|---|---| | [...ain/java/seedu/address/model/person/Volunteer.java](https://codecov.io/gh/AY2223S2-CS2103T-W12-1/tp/pull/280?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AY2223S2-CS2103T-W12-1#diff-c3JjL21haW4vamF2YS9zZWVkdS9hZGRyZXNzL21vZGVsL3BlcnNvbi9Wb2x1bnRlZXIuamF2YQ==) | `95.23% <100.00%> (+0.23%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AY2223S2-CS2103T-W12-1). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AY2223S2-CS2103T-W12-1)

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