[FAB-9117] Fix one misspelling of "legder" in Go code

I see no other such misspellings in the code base.

Change-Id: Iffb19e4c669104037eba860db485ed077bc4d30d
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>

Author: rpjday

core/deliverservice/requester.go

@@ -37,7 +37,7 @@ type blocksRequester struct {
 func (b *blocksRequester) RequestBlocks(ledgerInfoProvider blocksprovider.LedgerInfo) error {
 	height, err := ledgerInfoProvider.LedgerHeight()
 	if err != nil {
-		logger.Errorf("Can't get legder height for channel %s from committer [%s]", b.chainID, err)
+		logger.Errorf("Can't get ledger height for channel %s from committer [%s]", b.chainID, err)
 		return err
 	}