docs: kdoc_re: Change NestedMath args replacement to \0

Future patches will allow parsing each argument instead of the
hole set. Prepare for it by changing the replace all args from
\1 to \0.

No functional changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <46e383118be9d9e432e3814fe819ebb12261d7b4.1772469446.git.mchehab+huawei@kernel.org>

tools/lib/python/kdoc/kdoc_re.py

@@ -188,7 +188,7 @@ class NestedMatch:
     # except that the content inside the match group is delimiter-aligned.
     #
     # The content inside parentheses is converted into a single replace
-    # group (e.g. r`\1').
+    # group (e.g. r`\0').
     #
     # It would be nice to change such definition to support multiple
     # match groups, allowing a regex equivalent to:
@@ -291,7 +291,7 @@ class NestedMatch:
 
         if the sub argument contains::
 
-            r'\1'
+            r'\0'
 
         it will work just like re: it places there the matched paired data
         with the delimiter stripped.
@@ -310,9 +310,9 @@ class NestedMatch:
             # Value, ignoring start/end delimiters
             value = line[end:pos - 1]
 
-            # replaces \1 at the sub string, if \1 is used there
+            # replaces \0 at the sub string, if \0 is used there
             new_sub = sub
-            new_sub = new_sub.replace(r'\1', value)
+            new_sub = new_sub.replace(r'\0', value)
 
             out += new_sub