Add VGT Corpus to list of datasets

@misc{dataset:herreweghe2015VGTCorpus,
 author = {{Van Herreweghe, Mieke and Vermeerbergen, Myriam and Demey, Eline and De Durpel, Hannes and Nyffels, Hilde and Verstraete, Sam}},
 keywords = {{Vlaamse Gebarentaal,Corpuslinguïstiek}},
 language = {{dut}},
 title = {{Het Corpus VGT. Een digitaal open access corpus van videos and annotaties van Vlaamse Gebarentaal, ontwikkeld aan de Universiteit Gent ism KU Leuven. <www.corpusvgt.be>}},
 url = {{http://www.corpusvgt.ugent.be/}},
 year = {{2015}}
}

Additional Checklist for datasets:

When adding a dataset, follow the following steps. This pull request provides an example:

[x] Fork the repo
[x] sync forks
[x] git checkout master
[x] git pull
[x] New branch: dataset/something
[x] Create a JSON along the lines of the schema below. e.g. FOO.json
[x] Add the JSON to src/datasets. e.g. src/datasets/FOO.json
[x] Add BibTex to src/references.bib.
- [x] prepend the citation key with dataset. e.g. dataset:sehyr2021asl
- [x] "language" field should not need "sign language". No need to say "American Sign Language", "American" will do.
- [x] Very concise "samples" field, the table does not have a lot of space to display it.
[x] Commit/push the changes
[x] Make a pull request!

Schema:

{
  "pub": {
    "name": string, # this gets used as the name of the dataset, e.g. "WLASL"
    "year": integer or null,
    "publication":string or null, # this matches a key in references.bib, e.g. "dataset:joshiISLTranslateDatasetTranslating2023"
    "url": string or null # URL to access it. e.g. "https://www.sign-lang.uni-hamburg.de/dgs-korpus/index.php/welcome.html"
  },
  "#loader": string or null, # the key you would use in the sign language datasets library. e.g. "dgs_corpus". Website will auto-link
  "#items": integer or null, # this is the number of unique signs in the column
  "#samples": string or null, # e.g. "1100 videos" or "8,257 Sentences"
  "#signers": integer or string or null, # number of unique signers
  "features": array of strings, ["feature1","feature2"], # I've seen things like "mouthing", "video:RGB", "pose:Kinect", "pose:OpenPose","text:Polish", "gloss:ASL", "writing:HamNoSys", etc.
  "language": string, # the Sign language or languages, e.g. "American" for American Sign Language (ASL)
  "license": string or null,
  "licenseUrl": string or null
}

sign-language-processing / sign-language-processing.github.io

Add VGT Corpus to list of datasets #74