i18n(ja) Distribution Section (part 1 of 3)

[J1-takai]

Description

i18n(ja): Japanese translation of the first 7 files in "Distribution Section"

• First 7 files from "Overview" to "DMG" in the Distribution Section are translated into Japanese.
• Special NOTE: in the index.mdx (Overview file), a "Navigation Box" (<CardGrid> entry) to "AUR.mdx" is missing in the ##Distributing-###Linux section of the EN version. I added this in my JA version. Should be no harm.
• Closes #