Mark up "input" as in-line code

[solt87]

• [x] I provide my work under the project license.
• [x] I grant such license of my work as is required for the purposes of future print editions to Ben Straub and Scott Chacon.

Changes

• Adds in-line code markup to the word "input", as it is mentioned as a setting value.

Context

When mentioning the core.autocrlf value true, the text marks it up as in-line code. This patch applies the same markup to the input value of the same setting.

[ben]

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