Add a code of conduct and update documentation theme

[tsalo]

Closes None.

Changes proposed:

• Add a code of conduct with James as the enforcer.
• Update the contributing documentation to remove Tal as BDFL.
• Add Tom to the Zenodo file.
• Link to metafor in the "about" page.

[codecov-commenter]

Codecov Report

Merging #96 (15a7c33) into master (131445c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #96   +/-   ##
=======================================
  Coverage   87.44%   87.44%           
=======================================
  Files          13       13           
  Lines         844      844           
=======================================
  Hits          738      738           
  Misses        106      106           

Impacted Files	Coverage Δ
pymare/estimators/estimators.py	83.65% <ø> (ø)

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