Fix the Update Interpolation section on Event Loop page in Programming Guide

[pushfoo]

What's Broken?

1. Typo breaking the syntax
2. The example doesn't have a link to it or an example of how to run it
3. Multiple typos + broken syntax on https://api.arcade.academy/en/latest/programming_guide/event_loop.html
   The page source is https://github.com/pythonarcade/arcade/blob/development/doc/programming_guide/event_loop.rst

Source:

arcade/doc/programming_guide/event_loop.rst

Lines 98 to 105 in 8be3699

	Update Interpolation
	^^^^^^^^^^^^^^^^^^^^
	Because fixed updates work on the accumulation of time this may not sync with
	the ``on_draw`` or ``on_update`` events. In extreme cases this can cause a visible stuttering to
	objects moved within ``on_fixed_update``. To prevent this, ``GLOBAL_FIXED_CLOCK`` provides
	the ``accumulated`` and ``fraction``properties. By storing the last frame's position information it is possible
	to use ``fraction`` to interpolate towards the next calculated positions. For a visual representation of
	this effect look at ``arcade.examples.fixed_update_interpolation``.

Proposed Quick Fix

Note

Since fixes to the update / clock backends are actively being discussed, we'll leave adding a "proper" example thumbnail page till later.

• s/``fraction``properties/``fraction`` properties/ (add a space)

• Add temp link to GitHub instead of just a literal:

  For a visual representation of this, run the  `fixed_update_interpolation <https://github.com/pythonarcade/arcade/blob/development/arcade/examples/fixed_update_interpolation.py>`_ example as follows:
  
  .. code-block:: shell
     
     python -m arcade.examples.fixed_update_interpolation
  

• Elaborate on why / what you should pay attention below the code, covering these points:
  * It will run very slowly at first
  * Watch carefully and pay attention to the right-most yellow circle
  * It will not move smoothly

• Add method cross-refs for on_draw, on_update, and on_fixed_update by filling in the $EVENT_METHOD name as follows:

  :py:meth:`~Window.$EVENT_METHOD`
  

[harriebird]

Hi guys, please check PR #2598 for this issue.

[eruvanos]

Thank you, fixed