optimizing `first_kernel_ro_page` part 2 (#3395)

* optimizing `first_kernel_ro_page` part 2

* Improve comment clarity

Clarified comment about kernel text search optimization.

pwndbg/aglib/kernel/__init__.py

@@ -131,7 +131,9 @@ def first_kernel_ro_page() -> pwndbg.lib.memory.Page | None:
 
         if result:
             return mapping
-    for mapping in fallback_mappings:
+    # optimization: observe that the first Linux kernel region is the kernel text so search it last
+    # it now finds the first ro page almost instantly even for kernels that are partially initialized
+    for mapping in fallback_mappings[1:] + [fallback_mappings[0]]:
         # this loop handles when the kernel has not finished initialization
         # and the permission of the first ro page has not been properly set
         result = next(pwndbg.search.search(b"Linux version", mappings=[mapping]), None)