docs: Fix some broken references

As we move stuff around, some doc references are broken. Fix some of
them via this script:
	./scripts/documentation-file-ref-check --fix

Manually checked if the produced result is valid, removing a few
false-positives.

Acked-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/include/linux/assoc_array.h b/include/linux/assoc_array.h
index a89df3b..65e3832 100644
--- a/include/linux/assoc_array.h
+++ b/include/linux/assoc_array.h
@@ -1,6 +1,6 @@
 /* Generic associative array implementation.
  *
- * See Documentation/assoc_array.txt for information.
+ * See Documentation/core-api/assoc_array.rst for information.
  *
  * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
diff --git a/include/linux/assoc_array_priv.h b/include/linux/assoc_array_priv.h
index 711275e..a00a065 100644
--- a/include/linux/assoc_array_priv.h
+++ b/include/linux/assoc_array_priv.h
@@ -1,6 +1,6 @@
 /* Private definitions for the generic associative array implementation.
  *
- * See Documentation/assoc_array.txt for information.
+ * See Documentation/core-api/assoc_array.rst for information.
  *
  * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
diff --git a/include/linux/circ_buf.h b/include/linux/circ_buf.h
index 7cf262a..b3233e8 100644
--- a/include/linux/circ_buf.h
+++ b/include/linux/circ_buf.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * See Documentation/circular-buffers.txt for more information.
+ * See Documentation/core-api/circular-buffers.rst for more information.
  */
 
 #ifndef _LINUX_CIRC_BUF_H
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 9c3c9a3..8154f49 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1,7 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Ftrace header.  For implementation details beyond the random comments
- * scattered below, see: Documentation/trace/ftrace-design.txt
+ * scattered below, see: Documentation/trace/ftrace-design.rst
  */
 
 #ifndef _LINUX_FTRACE_H
diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
index e4b257f..bc8206a 100644
--- a/include/linux/rculist_nulls.h
+++ b/include/linux/rculist_nulls.h
@@ -109,7 +109,7 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
  *
  * The barrier() is needed to make sure compiler doesn't cache first element [1],
  * as this loop can be restarted [2]
- * [1] Documentation/atomic_ops.txt around line 114
+ * [1] Documentation/core-api/atomic_ops.rst around line 114
  * [2] Documentation/RCU/rculist_nulls.txt around line 146
  */
 #define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member)			\