chore: Improve message for capitalizing pronoun I

Old message was "First-person singular pronouns must be capitalized."

But English has two first-person singular pronouns: I & me.

Only I is capitalized. I changed the message to "The first-person singular subject pronoun must be capitalized."

"I" is also called the nomininative. I chose "subject" because it's a little less jargony for people less familiar with grammar and linguistics, and it's shorter when the message is already long.

Author: hippietrail

harper-core/src/linting/capitalize_personal_pronouns.rs

@@ -25,7 +25,8 @@ impl Linter for CapitalizePersonalPronouns {
                         span: tok.span,
                         lint_kind: LintKind::Capitalization,
                         suggestions: vec![Suggestion::ReplaceWith(vec!['I'])],
-                        message: "First-person singular pronouns must be capitalized.".to_string(),
+                        message: "The first-person singular subject pronoun must be capitalized."
+                            .to_string(),
                         priority: 31,
                     });
                 }