Remove old doc

doc/workflow/import_export/README.md

-# Project import/export
-
-Existing projects running on any GitLab instance or GitLab.com can be exported
-with all their related data and be moved into a new GitLab instance.
-
->**Note:** 
-  - This feature was [introduced][ce-3050] in GitLab 8.9
-  - Importing will not be possible if the import instance version is lower
-  than that of the exporter.
- 
-## Exported contents
- 
-- The following items will be exported:
-  - Project and wiki repositories
-  - Project uploads
-  - Project configuration including web hooks and services
-  - Issues with comments, merge requests with diffs and comments, labels, milestones, snippets,
-   and other project entities
-- The following items will NOT be exported:
-  - Build traces and artifacts
-  - LFS objects
-
-## Exporting a project and its data 
-
-1. Go to the project settings page and find the Export button
-
-    ![export_1](./img/export_1.png)
-
-1. Once the export is generated, you should receive an e-mail with a link to download the file
-
-    ![export_3](./img/export_3.png)
-
-1. You can come back to project settings and download the file from there, or delete it so it
-can be generated again
-
-    ![export_4](./img/export_4.png)
-
-## Importing the project
-
-1. The new GitLab project import feature is at the far right of the import options on New Project
-
-    ![import_1](./img/import_1.png)
-
-1. After choosing a namespace or path, you can then select the file exported previously
-
-    ![import_2](./img/import_2.png)
-
-1. Click on Import to begin importing  and you will see your newly imported project page soon
-
-
-## Advanced
-
-The GitLab Import/Export version can be checked by using:
-
-```bash
-sudo gitlab-rake gitlab:import_export:version
-```
-
-The current list of DB tables that will get exported can be listed by using:
-
-```bash
-sudo gitlab-rake gitlab:import_export:data
-```
-
-[ce-3050]: https://gitlab.com/gitlab-org/gitlab-ce/issues/3050