Fixing minor typos with regards to SUMO_HOME, refs #2

docs/web/docs/Developer/Tests.md

@@ -67,11 +67,11 @@ to collapse the static test suites on program start. E.g.:
 There are several packages being used by the tools under test. So if you want to run
 the "tools" and/or "complex" tests please do
 
-`pip3 install -r {{SUMO}}/tools/requirements.txt`
+`pip3 install -r $SUMO_HOME/tools/requirements.txt`
 
 # Running the Tests
 
-Within the  `{{SUMO}}/tests` folder you can find batch files for Windows and shell files for Linux & macOS which start
+Within the  `$SUMO_HOME/tests` folder you can find batch files for Windows and shell files for Linux & macOS which start
 [TextTest](https://texttest.org/) with our test suites. `runAllTests.bat` (Windows) or `runTests.sh` (Linux, macOS)
 starts TextTest for testing all applications located in the folder,
 `runNetconvertTests.bat` (Windows) will only show tests for netconvert,
@@ -93,7 +93,7 @@ To add a test suite for a new application, you have to perform the
 following steps. For the examples below we'll use "polyconvert" as the
 example application.
 
-- go to {{SUMO}}*/tests*
+- go to `$SUMO_HOME/tests`
 - copy one of the **run...Tests.bat**-files and rename it properly
   (**runPolyconvertTests.bat** in our case); change the name of the
   application within it. In our case the resulting file will look as