Update Pigweed presubmit

Updates the upstream presubmit to play nicely with The Great GN
Refactor.

Change-Id: I2296db592b4c8e3c2d5592410b9846e7435ac1fc
diff --git a/pw_allocator/docs.rst b/pw_allocator/docs.rst
index ae31c55..9604377 100644
--- a/pw_allocator/docs.rst
+++ b/pw_allocator/docs.rst
@@ -9,10 +9,10 @@
 This module provides various building blocks
 for a dynamic allocator. This is composed of the following parts:
 
-- ``block`` - An implementation of a linked list of memory blocks, supporting
-  splitting and merging of blocks.
-- ``freelist`` - A freelist, suitable for fast lookups of available memory
-  chunks (i.e. ``block``s)
+ - ``block``: An implementation of a linked list of memory blocks, supporting
+   splitting and merging of blocks.
+ - ``freelist``: A freelist, suitable for fast lookups of available memory
+   chunks (i.e. ``block`` s).
 
 Note, this module, and its documentation, is currently incomplete and
 experimental.