Proposing several changes

• regrouping workflow scripts
• reorganization of README sections (added some as suggestions too)
• added badges generated by HUMG (+ integrated in README)
• HUMG also updated metrics in htr-united.yml
• added a CC-BY 4.0 LICENSE to match info in README, although I would suggest clarifying what applies to what (right now you say the transcription are copyright free but the image are under Heidelberg's library copyright, yet the dataset is under CC-BY)
• added placeholder for a folder of static images, to add illustrations of the dataset, the transcription guidelines and any other logos
• added character table as generated by chocomufin

.github/workflows/HTRUC.yml

-# This workflow will install Python dependencies, run tests and lint with a single version of Python
-# For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions
-
-name: HTRUC
-
-on: [push, pull_request]
-
-jobs:
-  test:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-    - name: Set up Python 3.8
-      uses: actions/setup-python@v2
-      with:
-        python-version: 3.8
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip
-        pip install htruc
-    - name: Run HTRUC
-      run: |
-        htruc test htr-united.yml
\ No newline at end of file