Clarify that the file modifier isn't an access modifier, it's a different type of modifier.

[BillWagner]

Fixes #48224

Find all references to the file modifier, and remove or update any where the file modifier is referred to as an access modifier. It's classified differently to limit where it can be used, and how it can be applied.

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Internal previews

📄 File	🔗 Preview link
docs/csharp/fundamentals/program-structure/main-command-line.md	Main() and command-line arguments
docs/csharp/language-reference/keywords/access-modifiers.md	"Access Modifiers"
docs/csharp/language-reference/keywords/accessibility-levels.md	Accessibility levels (C# reference)
docs/csharp/programming-guide/classes-and-structs/access-modifiers.md	Access modifiers (C# programming guide)
docs/csharp/programming-guide/classes-and-structs/nested-types.md	docs/csharp/programming-guide/classes-and-structs/nested-types

[Copilot]

Pull request overview

This PR clarifies that the file modifier is not an access modifier, but rather a distinct type of modifier in C#. The documentation is updated across multiple files to reflect this important distinction by separating the description of file from the list of access modifiers.

Key Changes

• Reduces the count of access modifiers from 5 to 4 (removing file from the list)
• Reduces accessibility levels from 7 to 6
• Adds separate sections explaining that file is a distinct modifier that cannot be combined with access modifiers
• Removes the "(except file)" qualifier from the Main method documentation since file was never an access modifier
• Improves writing style throughout by converting to active voice and sentence case headings

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

File	Description
docs/csharp/programming-guide/classes-and-structs/access-modifiers.md	Separates file modifier documentation from access modifiers list, adds clarification that file cannot be combined with access modifiers, and applies sentence case to heading
docs/csharp/language-reference/keywords/accessibility-levels.md	Adds new section explaining file modifier separately from access modifiers table, updates heading to sentence case, and improves writing style
docs/csharp/language-reference/keywords/access-modifiers.md	Updates access modifier count from 5 to 4, changes accessibility level count from 7 to 6, and adds separate explanation of file modifier with note that it cannot be combined with access modifiers
docs/csharp/fundamentals/program-structure/main-command-line.md	Removes "(except file)" qualifier from Main method documentation since file is not an access modifier, and applies various writing style improvements

[ltrzesniewski]

I'm pretty sure the system doesn't store the return value in an environment variable (of which process would that be?). It's the shell which retrieves the exit code, and stores it in an internal variable (neither ERRORLEVEL nor LastExitCode are environment variables).