* Dropdown: Added slots to documentation

Added slots section in english to documentation for dropdown component. Chinese and Spanish missing.

* Update dropdown.md

* changelog for 2.4.8

* Update CHANGELOG.en-US.md

* Update CHANGELOG.es.md

* Tabs: fix not scrolling to active tab

* update tabs.vue

A textarea element can also have an autocomplete attribute.
Reference: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/textarea

* date-picker: fix confirm() ignoring date validity

make date-range panel's confirm validate date before confirming.

1. disable confirm button if picked date is invalid
2. reset highlight date on picker open (resetView)

* test: date-time-range confirm honors disabledDate

* [Button]Support Dropdown in ButtonGroup(#12815)

* [Button]Support Dropdown in ButtonGroup(#12815)

* [Button]Support Dropdown in ButtonGroup(#12815)

* Form: Emits error message on validate events

* Update form.md

* Tabs: fix order of TabNav when array is sorted

* update tabs.vue

* update test cases

Added Serbian translation.

Translate missing text

* Dialog: add opened event

* Docs: update es dialog doc

* Update dialog.md

* Form: adds prop to make asterisk optional on required  fields

* Form: adds prop to make asterisk optional on required  fields

* ElForm: Reverses attribute name to hide-required-asterisk, which defaults to false

* Update form-item.vue

* Update form.scss

* Update form.md

* update Spanish Doc

* update Spanish Doc

* update Spanish Doc

* Docs: Document el-form label-position attribute

Adds improved documentation to the el-form `label-position` attribute, which behaves differently when used with and without `label-width`. This has been a source of confusion for myself and others:

https://github.com/ElemeFE/element/issues/8477

Thanks!

* Document el-form label-position attribute (zh-CN, needs translation)

* Document el-form label-position attribute (es)

* Update form.md

* Select: use initial height to reset height of input

* Update select.vue

* Updated el-form-item to accept custom error message via slot

* FormItem: updated slot name in docs

* updated spanish and chinese translations

* Update form.md

* Update form.md

* Update form.md

* Update form.md

* Upload: create blob URL when picture displays

* Update index.vue

Current link is https://element.eleme.io/nuxtjs.org instead of https://nuxtjs.org/.