Merge branch 'simplify-create-new-list-issue-boards' into 'master'

Simplify copy on "Create a new list" dropdown in Issue Boards

## What does this MR do?

It changes the "Create new list" text to simply "Add list". It also describes the operation in a more concise way. It was suggested in #24659.

## Are there points in the code the reviewer needs to double check?

Although I refactored references to the name of the button to reflect the new text, I left part of the documentation unmodified:

File: `doc/user/project/issue_board.md`
```
In short, here's a list of actions you can take in an Issue Board:                 
                                                                                   
- [Create a new list](#creating-a-new-list).                                       
- [Delete an existing list](#deleting-a-list). 
```
because I was not sure if changing those was necessary.


Additionally, I replaced every occurrence of `click_button 'Create new list'` with `click_button 'Add list'`in the spec. I'm not sure if that causes any change in behavior as I am not sure if there are any hooks to the previous name, explicitly.

File: `spec/features/boards/boards_spec.rb`

## Why was this MR needed?

It is an improvement, as suggested in #24659

## Screenshots (if relevant)

**Before:**
![before](/uploads/cffd30b0e9a21d16bc25d046eb4ca42b/before.png)

**After:**
![after2](/uploads/95b049e0c1c565c4ccd1a72a3f4be925/after2.png)

## Does this MR meet the acceptance criteria?

- [X] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [X] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [X] All builds are passing
- [X] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [X] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [X] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [X] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
#24659

See merge request !7605

2 files changed, 5 insertions, 7 deletions

diff --git a/app/views/shared/issuable/_filter.html.haml b/app/views/shared/issuable/_filter.html.haml
index ed93857e6d4..b7e5e928993 100644
--- a/app/views/shared/issuable/_filter.html.haml
+++ b/app/views/shared/issuable/_filter.html.haml
@@ -40,9 +40,9 @@
               - if can?(current_user, :admin_list, @project)
                 .dropdown.pull-right
                   %button.btn.btn-create.js-new-board-list{ type: "button", data: { toggle: "dropdown", labels: labels_filter_path, namespace_path: @project.try(:namespace).try(:path), project_path: @project.try(:path) } }
-                    Create new list
+                    Add list
                   .dropdown-menu.dropdown-menu-paging.dropdown-menu-align-right.dropdown-menu-issues-board-new.dropdown-menu-selectable
-                    = render partial: "shared/issuable/label_page_default", locals: { show_footer: true, show_create: true, show_boards_content: true, title: "Create a new list" }
+                    = render partial: "shared/issuable/label_page_default", locals: { show_footer: true, show_create: true, show_boards_content: true, title: "Add list" }
                     - if can?(current_user, :admin_label, @project)
                       = render partial: "shared/issuable/label_page_create"
                     = dropdown_loading
diff --git a/app/views/shared/issuable/_label_page_default.html.haml b/app/views/shared/issuable/_label_page_default.html.haml
index c0dc63be2bf..a8f01026ca5 100644
--- a/app/views/shared/issuable/_label_page_default.html.haml
+++ b/app/views/shared/issuable/_label_page_default.html.haml
@@ -1,17 +1,15 @@
 - title = local_assigns.fetch(:title, 'Assign labels')
 - show_create = local_assigns.fetch(:show_create, true)
 - show_footer = local_assigns.fetch(:show_footer, true)
-- filter_placeholder = local_assigns.fetch(:filter_placeholder, 'Search labels')
+- filter_placeholder = local_assigns.fetch(:filter_placeholder, 'Search')
 - show_boards_content = local_assigns.fetch(:show_boards_content, false)
 .dropdown-page-one
   = dropdown_title(title)
   - if show_boards_content
     .issue-board-dropdown-content
       %p
-        Each label that exists in your issue tracker can have its own dedicated
-        list. Select a label below to add a list to your Board and it will
-        automatically be populated with issues that have that label. To create
-        a list for a label that doesn't exist yet, simply create the label below.
+        Create lists from the labels you use in your project. Issues with that
+        label will automatically be added to the list.
   = dropdown_filter(filter_placeholder)
   = dropdown_content
   - if @project && show_footer