various docstring fixes for web docs
ENH do not use plt.cm.jet in JL bound example

Also move the call to plt.show() to the end of the script
to avoid blocking the execution.
DOC fix kernels documentation inconsistencies

Fixes gh-3916, gh-2901.
Fix tinyclues logo in doc/about.rst

We updated our website and the logo URL was broken.
Merge pull request #3923 from Lothiraldan/patch-1

Fix tinyclues logo in doc/about.rst
Merge pull request #3921 from trevorstephens/docstring-format-fixes

[MRG+1] Various docstring fixes for web docs