Redo commit 7244ae9a98. The same trivial change was done with an online edit, but this resulted in some corruption of special characters in the file, likely because of differences with the character set used by the Bitbucket online editor.

Documentation/NuttxPortingGuide.html

@@ -422,7 +422,7 @@
   </li>
   <li>
     <i>Chip/SoC specific files</i>.
-    Each processor processor architecture is embedded in chip or <i>System-on-a-Chip</i> (SoC) architecture.
+    Each processor architecture is embedded in chip or <i>System-on-a-Chip</i> (SoC) architecture.
     The full chip architecture includes the processor architecture plus chip-specific interrupt logic,
     clocking logic, general purpose I/O (GPIO) logic, and specialized, internal peripherals (such as UARTs, USB, etc.).
     <p>