fix docs typo (resolve kazupon/kazupon#3)

kazupon · kazupon · commit 020ae5a75840 · 2020-12-17T10:44:47.000+09:00
diff --git a/docs/essentials/syntax.md b/docs/essentials/syntax.md
@@ -214,7 +214,7 @@ const i18n = createI18n({
   },
   // set custom modifiers at `modifiers` option
   modifiers: {
-    snakeCase: (str) => str.split(' ').join('-')
+    snakeCase: (str) => str.split(' ').join('_')
   }
 })
 ```

Original file line number	Diff line number	Diff line change
`@@ -214,7 +214,7 @@ const i18n = createI18n({`
`214`	`214`	`},`
`215`	`215`	// set custom modifiers at `modifiers` option
`216`	`216`	`modifiers: {`
`217`		`- snakeCase: (str) => str.split(' ').join('-')`
	`217`	`+ snakeCase: (str) => str.split(' ').join('_')`
`218`	`218`	`}`
`219`	`219`	`})`
`220`	`220`	```