Merge branch '20356-network-commit-hash-input-placeholder-corrections' into 'master'

Changed network input placeholder to 'Git revision'

## What does this MR do?

Changes the commit SHA-1 input placeholder on the network page to `Git revision`. ([as defined here](https://git-scm.com/docs/gitrevisions))

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

## Why was this MR needed?

Placeholder was too complex

## Screenshots (if relevant)

![Screen_Shot_2016-10-10_at_15.06.23](/uploads/e31586b0f7a973b04e55e73223a2a95c/Screen_Shot_2016-10-10_at_15.06.23.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [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
  - [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #20356

See merge request !6766

app/views/projects/network/show.html.haml

@@ -8,7 +8,7 @@
   .project-network
     .controls
       = form_tag namespace_project_network_path(@project.namespace, @project, @id), method: :get, class: 'form-inline network-form' do |f|
-        = text_field_tag :extended_sha1, @options[:extended_sha1], placeholder: "Input an extended SHA1 syntax", class: 'search-input form-control input-mx-250 search-sha'
+        = text_field_tag :extended_sha1, @options[:extended_sha1], placeholder: "Git revision", class: 'search-input form-control input-mx-250 search-sha'
         = button_tag class: 'btn btn-success' do
           = icon('search')
         .inline.prepend-left-20