docs: bpf: Fix bullet point formatting warning

Fix indentation for a bullet list item in bpf_iterators.rst.
According to reStructuredText rules, bullet list item bodies must be
consistently indented relative to the bullet. The indentation of the
first line after the bullet determines the alignment for the rest of
the item body.

Reported by smatch:
  /linux/Documentation/bpf/bpf_iterators.rst:55: WARNING: Bullet list ends without a blank line; unexpected unindent. [docutils]

Fixes: 7220eab ("bpf, docs: document open-coded BPF iterators")
Signed-off-by: Khaled Elnaggar <khaledelnaggarlinux@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250513015901.475207-1-khaledelnaggarlinux@gmail.com

Author: Khaled Elnaggar

Documentation/bpf/bpf_iterators.rst

@@ -52,14 +52,14 @@ a pointer to this `struct bpf_iter_<type>` as the very first argument.
 
 Additionally:
   - Constructor, i.e., `bpf_iter_<type>_new()`, can have arbitrary extra
-  number of arguments. Return type is not enforced either.
+    number of arguments. Return type is not enforced either.
   - Next method, i.e., `bpf_iter_<type>_next()`, has to return a pointer
-  type and should have exactly one argument: `struct bpf_iter_<type> *`
-  (const/volatile/restrict and typedefs are ignored).
+    type and should have exactly one argument: `struct bpf_iter_<type> *`
+    (const/volatile/restrict and typedefs are ignored).
   - Destructor, i.e., `bpf_iter_<type>_destroy()`, should return void and
-  should have exactly one argument, similar to the next method.
+    should have exactly one argument, similar to the next method.
   - `struct bpf_iter_<type>` size is enforced to be positive and
-  a multiple of 8 bytes (to fit stack slots correctly).
+    a multiple of 8 bytes (to fit stack slots correctly).
 
 Such strictness and consistency allows to build generic helpers abstracting
 important, but boilerplate, details to be able to use open-coded iterators