Add a README.md file

... because it is much nicer to have a project that explains what it is
all about.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

README.md

@@ -0,0 +1,20 @@
+# 7-Zip with an enhanced SFX component
+
+![7-Zip](https://www.7-zip.org/7ziplogo.png)
+
+Since its inception in 2007, Git for Windows made use of what was then called the "modified SFX" that used to be available from http://7zsfx.info. Sadly, that project seems to have gone defunct some time during 2016 and nobody seems to know why.
+
+Git for Windows used the "modified SFX" instead of the one shipped with [the official 7-Zip](http://7-zip.org/), for the following reasons:
+
+* The portable Git distribution wants to install into the final location rather than into a temporary directory (which would get deleted after the SFX ran the included `setup.exe`). The "modified SFX" supports configuration to ask the user where to extract/install the archive.
+* When canceling the installation, it is nice to be able to ask the user whether they are sure, and the "modified SFX" supported that.
+* The "modified SFX" allowed to set the window title of the "BeginPrompt" window as well as the progress window.
+
+This fork supports those needs of the portable Git for Windows package. The default branch always be the home for Git for Windows' modifications, switching to a new branch when newer 7-Zip version are released, rebasing the changes from the previous default branch.
+
+Please note that this project does not aim for a full replacement of the "modified SFX" so far:
+
+* there is no support yet for any of the `--sfxconfig`, `--sfxversion`, `--sfxlang`, `--sfxtest`, `--sfxwaitall`, and the `--sfxelevation` command-line option.
+* a *lot* of features are not reimplemented in this project, such as the `GUIMode`, the `GUIFlags`, or the `OverwriteMode` setting, just to name a few.
+
+Pull Requests that implement interesting and useful features are warmly welcome!