tqdm: add examples

pages/common/tqdm.md

@@ -1,8 +1,16 @@
 # tqdm
 
-> Create a progress bar.
+> Show progress over time of a command.
 > More information: <https://tqdm.github.io/>.
 
+- Show iterations per second and use stdout afterwards:
+
+`{{seq 10000000}} | tqdm | {{command}}`
+
 - Create a progress bar:
 
-`seq 10000000 | tqdm --total 10000000 --null`
+`{{seq 10000000}} | tqdm --total 10000000 | {{command}}`
+
+- Specify unit and total:
+
+`tar -zcf - {{docs/}} | tqdm --bytes --total $(du -sb {{docs/}} | cut -f1) > {{backup.tgz}}`