docs/devel/testing.rst: Update outdated Avocado URLs

Avocado documentation referred returns 404 error.
Update the broken links.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-Id: <20201010080741.2932406-1-philmd@redhat.com>

docs/devel/testing.rst

@@ -654,7 +654,7 @@ To manually install Avocado and its dependencies, run:
 
 Alternatively, follow the instructions on this link:
 
-  http://avocado-framework.readthedocs.io/en/latest/GetStartedGuide.html#installing-avocado
+  https://avocado-framework.readthedocs.io/en/latest/guides/user/chapters/installing.html
 
 Overview
 --------
@@ -837,7 +837,7 @@ Parameter reference
 To understand how Avocado parameters are accessed by tests, and how
 they can be passed to tests, please refer to::
 
-  http://avocado-framework.readthedocs.io/en/latest/WritingTests.html#accessing-test-parameters
+  https://avocado-framework.readthedocs.io/en/latest/guides/writer/chapters/writing.html#accessing-test-parameters
 
 Parameter values can be easily seen in the log files, and will look
 like the following: