update docs

docs/how-to-guides.md

@@ -149,26 +149,6 @@ We really pay attention to testing coverage, therefore to
 contribute we are expected to make tests and if possible increase
 the code coverage.
 
-To carry out testing, you need to prepare environment variables.
-For example, environment variables are found in the `.env.example`
-file. You can change the value according to what you have and save
-it in the root of the project directory with the file name `.env`.
-
-To set up environment variables we need `PASTEBIN_API_DEV_KEY`,
-`PASTEBIN_USERNAME`, and `PASTEBIN_PASSWORD`. `PASTEBIN_API_DEV_KEY`
-belongs to `PASTEBIN_USERNAME`. Then we also need `PASTEBIN_API_USER_KEY`,
-to get it we can make a login() API call. Please remember that
-`PASTEBIN_API_USER_KEY` MUST NOT belong to `PASTEBIN_USERNAME`,
-so simply we have to have two pastebin accounts.
-
-We have a doctest in src that we don't run it by default because
-it's for testing code examples in the docstring. The code example
-uses real API calls without mocks, it can cause the test to reach
-the API call rate limit. To run doctest, just open the `pyproject.toml`
-file and look at the `tool.pytest.ini_options` section in the
-`testpaths` configuration there is only a `tests` folder, you can
-add the `src` folder and run the test normally to run doctest in src.
-
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