Added 'Moderne-Physik' as a git submodule (and added hint in the README.md how to clone it completely)

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "documents/Moderne-Physik"]
+	path = documents/Moderne-Physik
+	url = https://github.com/parttimenerd/Moderne-Physik

README.md

@@ -1,10 +1,10 @@
 LaTeX-examples
 ==============
 
-More than 200 examples for the usage of LaTeX 
+More than 200 examples for the usage of LaTeX
 (you can check that with the following command: `find . -type d | sort | awk '$0 !~ last "/" {print last} {last=$0} END {print last}' | grep -v .git | wc -l`)
 
-Most examples can be found on [my Wikpedia Commons user page](http://commons.wikimedia.org/wiki/User:MartinThoma#Galerie).
+Many examples can be found on [my Wikpedia Commons user page](http://commons.wikimedia.org/wiki/User:MartinThoma#Galerie).
 
 You might also be interested in [my Blog](http://martin-thoma.com/tag/tikz/).
 
@@ -14,6 +14,12 @@ Usage
 Every LaTeX file is in a seperate folder and has its own Makefile.
 So you can simply generate the PDF by typing `make` in the terminal.
 
+If you want to get all examples offline, you have to execute
+
+```bash
+$ git clone --recursive https://github.com/MartinThoma/LaTeX-examples.git
+```
+
 Requirements
 ============
 
@@ -34,7 +40,7 @@ some images here
 
 Contact
 =======
-If you have examples or suggestions for improving given examples, 
+If you have examples or suggestions for improving given examples,
 please send them to info@martin-thoma.de.
 
 Re-use
@@ -42,7 +48,7 @@ Re-use
 Feel free to use and modify the examples in this repository,
 but please add a link to this repository or martin-thoma.com.
 
-*Most* of the content was created completely by me. But check 
+*Most* of the content was created completely by me. But check
 the Readme files in each specific folder to make sure you can use it.
 
 Other resources

documents/Moderne-Physik

@@ -0,0 +1 @@
+Subproject commit edaa9afed626737344b2930b82a19844f8820bb2