Fix a bunch of typos.

Fix a bunch of typos.

Most are in code comments, so nothing should break. UNKOWN_COMMAND and
CMD_UNKOWN are not used elsewhere, so correcting the spelling should
also not break anything.

src/server/startup.tcl

@@ -1,6 +1,6 @@
 # Defines basic Tcl procs for OpenOCD server modules
 
-# Handle GDB 'R' packet. Can be overriden by configuration script,
+# Handle GDB 'R' packet. Can be overridden by configuration script,
 # but it's not something one would expect target scripts to do
 # normally
 proc ocd_gdb_restart {target_id} {