ko: MDN writing guidelines 동기화

[SnowMarble]

#14373 에 따라 mdn/writing_guidelines을 업데이트합니다.

• index.md ko: writing guidelines #15069
• attrib_copyright_license ko: Attribution and copyright licensing #15212
• experimental_deprecated_obsolete
• howto (index.md) ko: How-to guides #15178 (MDN_Writing_guidelines_Howto.md 삭제)
  • creating_moving_deleting
  • document_a_css_property ko: How to document a CSS property #15181
  • document_an_http_header
  • document_web_errors ko: How to document web errors #15180
  • images_media
  • json_structured_data
  • markdown_in_mdn
  • research_technology
  • write_a_new_entry_in_the_glossary
  • write_an_api_reference (index.md)
    • information_contained_in_a_webidl_file
    • sidebars (MDN_Writing_guidelines_Howto_Write_an_API_reference_Sidebars.md 삭제)
• page_structures (index.md) ko: Page structures #15184
  • banners_and_notices ko: Banners and notices #15207
  • code_examples
  • compatibility_tables
  • live_samples
  • macros (index.md)
    • commonly_used_macros
    • other
  • page_types (index.md)
    • api_constructor_subpage_template
    • api_event_subpage_template
    • api_landing_page_template
    • api_method_subpage_template
    • api_property_subpage_template
    • api_reference_page_template
    • aria_page_template
    • css_module_landing_page_template
    • css_property_page_template
    • css_selector_page_template
    • glossary_page_template
    • html_element_page_template
    • http_header_page_template
    • page_type_key
    • svg_element_page_template
  • quicklinks
  • specification_tables
  • syntax_sections
• what_we_write (index.md)
  • criteria_for_inclusion
• writing_style_guide (index.md)
  • code_style_guide (index.md)
    • css
    • html
    • javascript
    • shell