docs: Fix typo in obs_enum_canvases description

[psyirius]

Description

Fixes documentation of obs_enum_canvases where in description instead of obs_canvas_get_weak_canvas to retain a weak reference it says obs_canvas_get_weak_encoder.

Motivation and Context

https://docs.obsproject.com/reference-core#c.obs_enum_canvases

How Has This Been Tested?

checked the rendered output.

Types of changes

• Documentation (a change to documentation pages)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[RytoEX]

Capitalize "fix" as "Fix". Do not use backticks in commit messages or PR titles.

docs: Fix typo in obs_enum_canvases description

[psyirius]

Capitalize "fix" as "Fix". Do not use backticks in commit messages or PR titles.

docs: Fix typo in obs_enum_canvases description

Done.