Add TFS migration docs

doc/user/project/import/index.md

@@ -8,6 +8,7 @@
 1. [From SVN](svn.md)
 1. [From ClearCase](clearcase.md)
 1. [From Perforce](perforce.md)
+1. [From TFS](tfs.md)
 
 In addition to the specific migration documentation above, you can import any
 Git repository via HTTP from the New Project page. Be aware that if the

doc/user/project/import/tfs.md

+# Migrating from TFS
+
+[TFS](https://www.visualstudio.com/tfs/) is a set of tools developed by Microsoft
+which also includes a centralized version control system (TFVC) similar to Git.
+
+In this document, we emphasize on the TFVC to Git migration.
+
+## TFVC vs Git
+
+The following list illustrates the main differences between TFVC and Git:
+
+- **Git is distributed** whereas TFVC is centralized using a client-server
+  architecture. This translates to Git having a more flexible workflow since
+  your working area is a copy of the entire repository. This decreases the
+  overhead when switching branches or merging for example, since you don't have
+  to communicate with a remote server.
+- **Changesets.** Changes in CVS are per file, while changes (commits) in Git
+  they always refer to the whole project. One of the consequences of this is that
+  it is very easy in Git to revert (create a change that undoes) or undo a whole
+  change.
+
+_Check also Microsoft's documentation on the
+[comparison of Git and TFVC](https://www.visualstudio.com/en-us/docs/tfvc/comparison-git-tfvc)
+and the Wikipedia article on
+[comparing the different version control software](https://en.wikipedia.org/wiki/Comparison_of_version_control_software)._
+
+## Why migrate
+
+Migrating to Git/GitLab there is:
+
+- **No licensing costs**, Git is GPL while TFVC is proprietary.
+- **Shorter learning curve**, Git has a big community and a vast number of
+  tutorials to get you started.
+- **Integration with modern tools**, migrating to Git and GitLab you can have
+  an open source end-to-end software development platform with built-in version
+  control, issue tracking, code review, CI/CD, and more.
+
+## How to migrate
+
+The best option to migrate from TFVC to Git is to use the
+[`git-tfs`](https://github.com/git-tfs/git-tfs) tool. A specific guide for the
+migration exists:
+[Migrate TFS to Git](https://github.com/git-tfs/git-tfs/blob/master/doc/usecases/migrate_tfs_to_git.md).