fix typos in tutorial.md (iovisor#2584)

fix typos in tutorial.md

Author: seeekr

docs/tutorial.md

@@ -97,7 +97,7 @@ TIME     COMM           PID    T BYTES   OFF_KB   LAT(ms) FILENAME
 
 ext4slower traces the ext4 file system and times common operations, and then only prints those that exceed a threshold.
 
-This is great for identifying or exonerating one type of performance issue: slow individually slow disk i/O via the file system. Disks process I/O asynchronously, and it can be difficult to associate latency at that layer with the latency applications experience. Tracing higher up in the kernel stack, at the VFS -> file system interface, will more closely match what an application suffers. Use this tool to identify if file system latency exceeds a given threshold.
+This is great for identifying or exonerating one type of performance issue: show individually slow disk i/O via the file system. Disks process I/O asynchronously, and it can be difficult to associate latency at that layer with the latency applications experience. Tracing higher up in the kernel stack, at the VFS -> file system interface, will more closely match what an application suffers. Use this tool to identify if file system latency exceeds a given threshold.
 
 Similar tools exist in bcc for other file systems: btrfsslower, xfsslower, and zfsslower. There is also fileslower, which works at the VFS layer and traces everything (although at some higher overhead).
 
@@ -151,7 +151,7 @@ TIME(s)        COMM           PID    DISK    T  SECTOR    BYTES   LAT(ms)
 
 biosnoop prints a line of output for each disk I/O, with details including latency (time from device issue to completion).
 
-This allows you to examine disk I/O in more detail, and look for time-ordered patterns (eg, reads queueing behind writes). Note that the output will be verbose if your system performance a high rate of disk I/O.
+This allows you to examine disk I/O in more detail, and look for time-ordered patterns (eg, reads queueing behind writes). Note that the output will be verbose if your system performs disk I/O at a high rate.
 
 More [examples](../tools/biosnoop_example.txt).