docs: uniform appCommands example code

[DraconicDragon]

Description

Changes context to ctx in the Application Commands articles' example code to match the rest of the documentation.

Type of change

Please delete options that are not relevant.

• This change requires a documentation update

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

@Aiko-IT-Systems/discatsharp

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