Adding JOSS Paper Draft to Main

[taylorbell57]

This PR does the following:

1. Adds the current JOSS paper draft to the main branch (with all current referee-requested edits implemented)
2. Adds some details to the documentation to address JOSS referee requests
3. Simplifies the inputdir and outputdir examples in ECF templates
4. Removes sys.path.append(f'..{os.sep}..{os.sep}') code meant only for working with uninstalled code from run_eureka.py files
5. Adds a README to the demos folder in case somebody gets there before reading the documentation page

[codecov-commenter]

Codecov Report

Merging #477 (bac289f) into main (4f785c1) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #477   +/-   ##
=======================================
  Coverage   59.45%   59.45%           
=======================================
  Files          75       75           
  Lines        8891     8891           
=======================================
  Hits         5286     5286           
  Misses       3605     3605           

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