docs: Fix a few typos

There are small typos in:
- apps/blehr/src/main.c
- apps/ext_advertiser/src/main.c
- nimble/controller/src/ble_ll.c
- nimble/host/src/ble_att_svr.c
- nimble/host/src/ble_hs_mbuf.c
- nimble/host/src/ble_sm.c

Fixes:
- Should read `response` rather than `respose`.
- Should read `measurement` rather than `measurment`.
- Should read `largest` rather than `larget`.
- Should read `instance` rather than `nstance`.
- Should read `application` rather than `applicaiton`.
- Should read `always` rather than `alwyas`.

apps/blehr/src/main.c

@@ -111,7 +111,7 @@ blehr_tx_hrate_stop(void)
     os_callout_stop(&blehr_tx_timer);
 }
 
-/* Reset heartrate measurment */
+/* Reset heartrate measurement */
 static void
 blehr_tx_hrate_reset(void)
 {

apps/ext_advertiser/src/main.c

@@ -421,7 +421,7 @@ static void start_periodic(void)
     ble_addr_t addr;
     int rc;
 
-    /* For periodic we use nstance with non-connectable advertising */
+    /* For periodic we use instance with non-connectable advertising */
     memset (&params, 0, sizeof(params));
 
     /* advertise using random addr */