some small improvements in English

chapters/entwicklungsumgebungen.qmd

@@ -43,7 +43,7 @@ julia>
 
 ### Jupyterhub & Jupyter
 
-- [Jupyterhub](https://de.wikipedia.org/wiki/Project_Jupyter) is a multi-user server for Jupyter.
+- [JupyterHub](https://de.wikipedia.org/wiki/Project_Jupyter) is a multi-user server for Jupyter notebooks.
 - Jupyter is a web-based interactive programming environment that
 - was originally written for and in Python, but now supports many programming languages
 - In Jupyter, one works with so-called *notebooks*. These are structured text files (JSON), recognizable by the file extension `*.ipynb`.
@@ -65,7 +65,7 @@ This can be used to:
 
 - open existing *notebooks*,
 - create new *notebooks*,
-- upload files, e.g. *notebooks*, from the local computer,
+- upload files, e.g., notebooks, from a local computer,
 - end the session with `Logout` (please don't forget!). 
 
 ### Jupyter notebooks
@@ -120,7 +120,7 @@ The cell currently being worked on can be in `command mode` or `edit mode`.
 :::
 
 
-When a cell is "working", its cell number becomes a `*` and
+When a cell is working, its cell number becomes a `*` and
 the `kernel busy` indicator (solid black dot at the top right next to the
 Julia version) appears. If this takes too long (an *infinite loop*
 is quickly programmed), then
@@ -130,7 +130,7 @@ is quickly programmed), then
 
 
 ::: {.callout-important }
-After a `kernel restart`, all cells containing required definitions,
+After a `kernel restart`, all cells containing the required definitions,
 `using` statements, etc. must be executed again.