fixes from PR comments

Author: jrozek

.gitignore

@@ -7,8 +7,10 @@ build
 __pycache__
 tests/test_django/db.sqlite3
 htmlcov
-.coverage
 
 # pytest-cov
 .coverage*
 coverage.xml
+
+# macOS
+.DS_Store

README.md

@@ -37,7 +37,7 @@ Install the package in editable mode and make sure that `django` and
 `pytest-django` are not installed.
 
 ```bash
-pip install -e .[tests]
+pip install -e ".[tests]"
 pip uninstall django pytest-django
 ```
 
@@ -50,7 +50,7 @@ Then follow the instructions in
 Install the package in editable mode along with Django dependencies:
 
 ```bash
-pip install -e .[django,tests,django_tests]
+pip install -e ".[django,tests,django_tests]"
 ```
 
 Then follow the instructions in 
@@ -72,10 +72,10 @@ To run tests in parallel, use the following command.
 pytest -v -n auto
 ```
 
-To run tests with coverage, use the following command.
+To run coverage tests, use the following command.
 
 ```bash
 pytest -v --cov=sio3pack --cov-report=html
 ```
 
-Coverage report will be generated in the `htmlcov/index.html`.
+The coverage report will be generated in the file `htmlcov/index.html`.