docs: annotate newly added features with version tag

docs/content/en/api.md

@@ -57,7 +57,7 @@ All [Vue I18n properties and methods](http://kazupon.github.io/vue-i18n/api/#vue
 
   See also [Basic usage - nuxt-link](../basic-usage#nuxt-link).
 
-#### $nuxtI18nHead
+#### $nuxtI18nHead <badge>v6.19.0+</badge>
 
   - **Arguments**:
     - options: (type: [`NuxtI18nHeadOptions`](https://github.com/nuxt-community/i18n-module/blob/master/types/nuxt-i18n.d.ts))
@@ -66,7 +66,7 @@ All [Vue I18n properties and methods](http://kazupon.github.io/vue-i18n/api/#vue
   If `options.addDirAttribute` is set to `false`, the `dir` attribute will not be added.
   If `options.addSeoAttributes` is set to `true`, the seo attributes will be added.
 
-#### $nuxtI18nSeo <badge>deprecated (use `$nuxtI18nHead`)</badge>
+#### $nuxtI18nSeo <badge>deprecated from v6.19.0 (use `$nuxtI18nHead`)</badge>
 
   - **Arguments**:
     - no arguments
@@ -118,7 +118,7 @@ Instance of [VueI18n class](http://kazupon.github.io/vue-i18n/api/#vuei18n-class
 
 ### Properties
 
-#### defaultDirection
+#### defaultDirection <badge>v6.19.0+</badge>
 
   - **Type**: `Directions`
 

docs/content/en/options-reference.md

@@ -66,7 +66,7 @@ When using an object form, the properties can be:
   * ISO 639-1 code (e.g. `'en'`)
   * ISO 639-1 and ISO 3166-1 alpha-2 codes, separated by hyphen (e.g. `'en-US'`)
 - `file` (required when using [`lazy`](#lazy)) - the name of the file. Will be resolved relative to `langDir` path when loading locale messages lazily
-- `dir`  The dir property specifies the direction of the elements and content, value could be `'rtl'`, `'ltr'` or `'auto'`.
+- `dir` (from `v6.19.0`)  The dir property specifies the direction of the elements and content, value could be `'rtl'`, `'ltr'` or `'auto'`.
 - `domain` (required when using [`differentDomains`](#differentdomains)) - the domain name you'd like to use for that locale (including the port if used)
 - `...` - any custom property set on the object will be exposed at runtime. This can be used, for example, to define the language name for the purpose of using it in a language selector on the page.
 
@@ -86,7 +86,7 @@ export default {
 
 </alert>
 
-## `defaultDirection`
+## `defaultDirection` <badge>v6.19.0+</badge>
 
 - type: `string`
 - default: `ltr`

docs/content/es/api.md

@@ -57,7 +57,7 @@ Todos los [Vue I18n propiedades y métodos](http://kazupon.github.io/vue-i18n/ap
 
   See also [Basic usage - nuxt-link](../basic-usage#nuxt-link).
 
-#### $nuxtI18nHead
+#### $nuxtI18nHead <badge>v6.19.0+</badge>
 
   - **Arguments**:
     - options: (type: [`NuxtI18nHeadOptions`](https://github.com/nuxt-community/i18n-module/blob/master/types/nuxt-i18n.d.ts))
@@ -66,7 +66,7 @@ Todos los [Vue I18n propiedades y métodos](http://kazupon.github.io/vue-i18n/ap
   If `options.addDirAttribute` is set to `false`, the `dir` attribute will not be added.
   If `options.addSeoAttributes` is set to `true`, the seo attributes will be added.
 
-#### $nuxtI18nSeo <badge>deprecated (use `$nuxtI18nHead`)</badge>
+#### $nuxtI18nSeo <badge>deprecated from v6.19.0 (use `$nuxtI18nHead`)</badge>
 
   - **Arguments**:
     - no arguments
@@ -118,7 +118,7 @@ Instance of [VueI18n class](http://kazupon.github.io/vue-i18n/api/#vuei18n-class
 
 ### Properties
 
-#### defaultDirection
+#### defaultDirection <badge>v6.19.0+</badge>
 
   - **Type**: `Directions`
 

docs/content/es/options-reference.md

@@ -66,7 +66,7 @@ When using an object form, the properties can be:
   * ISO 639-1 code (e.g. `'en'`)
   * ISO 639-1 and ISO 3166-1 alpha-2 codes, separated by hyphen (e.g. `'en-US'`)
 - `file` (required when using [`lazy`](#lazy)) - the name of the file. Will be resolved relative to `langDir` path when loading locale messages lazily
-- `dir`  The dir property specifies the direction of the elements and content, value could be `'rtl'`, `'ltr'` or `'auto'`.
+- `dir` (from `v6.19.0`)  The dir property specifies the direction of the elements and content, value could be `'rtl'`, `'ltr'` or `'auto'`.
 - `domain` (required when using [`differentDomains`](#differentdomains)) - the domain name you'd like to use for that locale (including the port if used)
 - `...` - any custom property set on the object will be exposed at runtime. This can be used, for example, to define the language name for the purpose of using it in a language selector on the page.
 
@@ -86,7 +86,7 @@ export default {
 
 </alert>
 
-## `defaultDirection`
+## `defaultDirection` <badge>v6.19.0+</badge>
 
 - type: `string`
 - default: `ltr`