Documentation doesn't compile

[jacob-rosenthal]

Need to fix bugs in documentation. Should also add tests to make sure that docs compile successfully.

(pathml) jupyter@shared-dxvm-gpu:~/pathml/docs$ make html
Running Sphinx v3.4.2
making output directory... done
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 17 source files that are out of date
updating environment: [new config] 17 added, 0 changed, 0 removed
/home/jupyter/pathml/pathml/preprocessing/multiparametricslide.py:16: UserWarning: MultiparametricSlide2d requires a jvm to interface with java bioformats library.
            See: https://pythonhosted.org/javabridge/installation.html. You can install using:
                
                sudo apt-get install openjdk-8-jdk
                pip install javabridge
                pip install python-bioformats
        
  warn(
WARNING: autodoc: failed to import module 'multiparametricslide' from module 'pathml.preprocessing'; the following exception was raised:
MultiparametricSlide2d requires javabridge and bioformats

Notebook error:
Problems with linked notebook "examples/link_advanced_HE_chunks" path:
InputError: [Errno 2] No such file or directory: '../examples/advanced_HE_chunks.ipynb'.
make: *** [Makefile:20: html] Error 2

Note that this issue is about the error in compilation. The javabridge warning should be fixed when we fix #48