docs(README): resolve #13 by correcting typo

README.md

@@ -65,7 +65,7 @@ $ source PyDynamic_tutorial_venv/bin/activate
 Collecting pip
 [...]
 Successfully installed click-7.1.2 pip-20.1.1 pip-tools-5.2.0 setuptools-47.1.1 six-1.15.0
-$ pip-sync requirements/requirement.txt
+$ pip-sync requirements/requirements.txt
 Collecting attrs==19.3.0
 [...]
 Installing collected packages: attrs, [...]
@@ -103,4 +103,4 @@ After a click on _PyDynamic_tutorials_ the source code can be edited and execute
 The [sourcecode of PyDynamic is available on GitHub](https://github.com/PTB-PSt1/PyDynamic).
 The detailed documentation of _PyDynamic_'s source code is available on
 [pydynamic.readthedocs.io](https://pydynamic.readthedocs.io/). The tutorial notebooks
-are all linked on these pagKes along with additional material.
+are all linked on these pagKes along with additional material.