docs: conf: don't rely on cwd to get documentation location

Instead of relying that Sphinx will be called from Documentation/
dir, pick the location based on __file__.

Suggested-by: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <34c38718dfade91ff6f7afca5e9c1705ba253c97.1768838938.git.mchehab+huawei@kernel.org>

Author: mchehab

Documentation/conf.py

@@ -13,10 +13,11 @@
 
 import sphinx
 
-# If extensions (or modules to document with autodoc) are in another directory,
-# add these directories to sys.path here. If the directory is relative to the
-# documentation root, use os.path.abspath to make it absolute, like shown here.
-sys.path.insert(0, os.path.abspath("sphinx"))
+# Location of Documentation/ directory
+kern_doc_dir = os.path.dirname(os.path.abspath(__file__))
+
+# Add location of Sphinx extensions
+sys.path.insert(0, os.path.join(kern_doc_dir, "sphinx"))
 
 # Minimal supported version
 needs_sphinx = "3.4.3"
@@ -32,9 +33,6 @@
     # Include patterns that don't contain directory names, in glob format
     include_patterns = ["**.rst"]
 
-# Location of Documentation/ directory
-kern_doc_dir = os.path.abspath(".")
-
 # Exclude of patterns that don't contain directory names, in glob format.
 exclude_patterns = []