stressapptest: add page (#10659)

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/common/stressapptest.md

@@ -0,0 +1,16 @@
+# stressapptest
+
+> Userspace memory and IO test.
+> More information: <https://github.com/stressapptest/stressapptest>.
+
+- Test the given amount of memory (in Megabytes):
+
+`stressapptest -M {{memory}}`
+
+- Test memory as well as I/O for the given file:
+
+`stressapptest -M {{memory}} -f {{path/to/file}}`
+
+- Test specifying the verbosity level, where 0=lowest, 20=highest, 8=default:
+
+`stressapptest -M {{memory}} -v {{level}}`