DOC [STYLE]: Change theme to clearer and more readable one

Author: xtrollyj00

.github/workflows/doc.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Setup and build
         run: |
           sudo apt-get install python3-pip
-          pip3 install sphinx sphinx-vhdl sphinx_rtd_theme piccolo_theme GitPython
+          pip3 install sphinx sphinx-vhdl sphinx_rtd_theme furo GitPython
           mkdir public
           mkdir public/html
           cp doc/source/index.html public/html/

.gitlab-ci.yml

@@ -16,7 +16,7 @@ pages:
     - apk add git
     - pip install -U GitPython
     - pip install -U sphinx
-    - pip install -U piccolo_theme
+    - pip install -U furo
     - pip install -U sphinx-vhdl
     - echo "Hotfix detached head, causing trouble in GitPython:"
     - git checkout $CI_COMMIT_BRANCH

README.md

@@ -60,7 +60,7 @@ First, you need to install a few Python packages:
 $ pip3 install --user GitPython
 $ pip3 install --user sphinx
 $ pip3 install --user sphinx-vhdl
-$ pip3 install --user piccolo_theme
+$ pip3 install --user furo
 ```
 
 Then the documentation is generated simply by issuing these two commands: