Clarify the start and end of scan intervals

Update the documentation of NetworkScanRequest to clarify
that the interval between scans is from the completion of
one scan to the start of another. This is the only possible
definition that doesn't possibly result in back-to-back
scans which never complete.

In the initial design of this API, the stated use case was
for scans where "interval" >> "scan duration". For that
use case, this clarification doesn't make a meaningful
difference; however, for the use case of long-duration
scans, the distinction prevents the issue stated above.

Bug: 139935383
Test: compilation (docstring-only change)
Change-Id: Ib8393110bfd3ea883045648ee7dac9c6e6a32d44
diff --git a/current.txt b/current.txt
index 3fabd7c..6f9f4d4 100644
--- a/current.txt
+++ b/current.txt
@@ -576,5 +576,6 @@
 eb2fa0c883c2185d514be0b84c179b283753ef0c1b77b45b4f359bd23bba8b75 android.hardware.neuralnetworks@1.0::IPreparedModel
 fb382e986c10b8fbb797a8546e8f9ea6d1107bfe6f3fb7e57f6bbbf1f807a906 android.hardware.neuralnetworks@1.2::IDevice
 40e71cd693de5b832325c5d8f081f2ff20a7ba2b89d401cee5b4b3eb0e241681 android.hardware.neuralnetworks@1.2::IPreparedModel
+a785a57447a81e9c130eef6904c3a5c256076c6a04588c40620ebd6fa2660d77 android.hardware.radio@1.2::types
 1a6e2bd289f22931c526b21916910f1d4c436b7acb9556e4243de4ce8e6cc2e4 android.hardware.soundtrigger@2.0::ISoundTriggerHwCallback
 fd65298e1e09e0e3c781ab18305920d757dbe55a3b459ce17814ec5cf6dfee99 android.hardware.wifi@1.0::IWifiP2pIface