Merge branch '25534-adding-a-way-to-go-back-on-error-pages' into 'master'

added go back anchor on error pages

## What does this MR do?

adds go back anchor on error pages

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

## Why was this MR needed?

requested per https://gitlab.com/gitlab-org/gitlab-ce/issues/25534

## Screenshots (if relevant)

![image](/uploads/894c513e7a058deb0124b5152dc11e28/image.png)

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) 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 #25534

See merge request !8087

changelogs/unreleased/25534-adding-a-way-to-go-back-on-error-pages.yml

+---
+title: Added go back anchor on error pages.
+merge_request: 8087
+author:

public/404.html

@@ -46,6 +46,14 @@
       margin: 40px auto;
     }
 
+    a {
+      line-height: 100px;
+      font-weight: normal;
+      color: #4A8BEE;
+      font-size: 18px;
+      text-decoration: none;
+    }
+
     .container {
       margin: auto 20px;
     }
@@ -63,6 +71,7 @@
     <hr />
     <p>Make sure the address is correct and that the page hasn't moved.</p>
     <p>Please contact your GitLab administrator if you think this is a mistake.</p>
+    <a href="javascript:history.back()">Go back</a>
   </div>
 </body>
 </html>

public/422.html

@@ -46,6 +46,14 @@
       margin: 40px auto;
     }
 
+    a {
+      line-height: 100px;
+      font-weight: normal;
+      color: #4A8BEE;
+      font-size: 18px;
+      text-decoration: none;
+    }
+
     .container {
       margin: auto 20px;
     }
@@ -63,6 +71,7 @@
     <hr />
     <p>Make sure you have access to the thing you tried to change.</p>
     <p>Please contact your GitLab administrator if you think this is a mistake.</p>
+    <a href="javascript:history.back()">Go back</a>
   </div>
 </body>
 </html>

public/500.html

@@ -46,6 +46,14 @@
       margin: 40px auto;
     }
 
+    a {
+      line-height: 100px;
+      font-weight: normal;
+      color: #4A8BEE;
+      font-size: 18px;
+      text-decoration: none;
+    }
+
     .container {
       margin: auto 20px;
     }
@@ -63,6 +71,7 @@
     <hr />
     <p>Try refreshing the page, or going back and attempting the action again.</p>
     <p>Please contact your GitLab administrator if this problem persists.</p>
+    <a href="javascript:history.back()">Go back</a>
   </div>
 </body>
 </html>

public/502.html

@@ -46,6 +46,14 @@
       margin: 40px auto;
     }
 
+    a {
+      line-height: 100px;
+      font-weight: normal;
+      color: #4A8BEE;
+      font-size: 18px;
+      text-decoration: none;
+    }
+
     .container {
       margin: auto 20px;
     }
@@ -63,6 +71,7 @@
     <hr />
     <p>Try refreshing the page, or going back and attempting the action again.</p>
     <p>Please contact your GitLab administrator if this problem persists.</p>
+    <a href="javascript:history.back()">Go back</a>
   </div>
 </body>
 </html>

public/503.html

@@ -46,6 +46,14 @@
       margin: 40px auto;
     }
 
+    a {
+      line-height: 100px;
+      font-weight: normal;
+      color: #4A8BEE;
+      font-size: 18px;
+      text-decoration: none;
+    }
+
     .container {
       margin: auto 20px;
     }
@@ -63,6 +71,7 @@
     <hr />
     <p>Try refreshing the page, or going back and attempting the action again.</p>
     <p>Please contact your GitLab administrator if this problem persists.</p>
+    <a href="javascript:history.back()">Go back</a>
   </div>
 </body>
 </html>