Fix: openpmd-pipe --help (#1069)

* Little fix in openpmd-pipe docu
* Update src/binding/python/openpmd_api/pipe/__main__.py

Co-authored-by: Axel Huebl <axel.huebl@plasma.ninja>

Author: franzpoeschel

src/binding/python/openpmd_api/pipe/__main__.py

@@ -46,8 +46,9 @@ def parse_args(program_name):
 with the largest extent.
 
 Examples:
-    {0} --infile simData.h5 simData_%T.bp
-    {0} --infile simData.sst --inconfig @streamConfig.json simData_%T.bp
+    {0} --infile simData.h5 --outfile simData_%T.bp
+    {0} --infile simData.sst --inconfig @streamConfig.json \\
+        --outfile simData_%T.bp
     {0} --infile uncompressed.bp \\
         --outfile compressed.bp --outconfig @compressionConfig.json
 """.format(os.path.basename(program_name)))