Fix up some comments in addCountmeFlag()

The buckets aren't really an array that's indexed in the code, they're
just sequential numbers for the URL flag.  Also clarify why we're using
"this window" instead of "the current position of the sliding window" in
the comments.

libdnf/repo/Repo.cpp

@@ -873,6 +873,9 @@ void Repo::Impl::addCountmeFlag(LrHandle *handle) {
      * This is to align the time window with an absolute point in time rather
      * than the last counting event (which could facilitate tracking across
      * multiple such events).
+     *
+     * In the below comments, the window's current position will be referred to
+     * as "this window" for brevity.
      */
     auto logger(Log::getLogger());
 
@@ -933,7 +936,7 @@ void Repo::Impl::addCountmeFlag(LrHandle *handle) {
         for (i = 0; i < COUNTME_BUCKETS.size(); ++i)
             if (step < COUNTME_BUCKETS[i])
                 break;
-        int bucket = i + 1;  // Buckets are indexed from 1
+        int bucket = i + 1;  // Buckets are numbered from 1
 
         // Set the flag
         std::string flag = "countme=" + std::to_string(bucket);