Spelling fixes in comments, documentation, tests and examples

By klemens <ka7@github.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 881512c..c45a0af 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -1460,7 +1460,7 @@
 					already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
 					continue;
 				}
-				/* Else: an error occured, panic! */
+				/* Else: an error occurred, panic! */
 				bb_perror_msg_and_die("select");
 			}
 		}