Improve SysFont documentation and add font verification warning. Closes #2643

[mv805]

Hello. This is my propsal to solve the usability issue noted here #2643 where I give my analysis into the issue.
I decided just to update the docs with a minor clarification and improve the warning to help prompt future users to double check their name inputs. This should prevent the issue from occuring as long as the user reads the docs and warnings 😃

The following short code can be ran to confirm the new warning:

import pygame
pygame.init()

font_size = 20  # some default font they might want

font = pygame.font.SysFont(pygame.font.get_default_font(), font_size)  # gives warning and defaults to freesansbold. Now you should see the updated warning prompting to double check name input.

print("Font loaded:", font.name)  # confirm that freesansbold loaded by default

pygame.quit()

[ankith26]

LGTM, thanks for contributing! 🥳

[gresm]

LGTM 👍