term: fix some comments

Change-Id: I8211158071d0a657d0097aba242278fa4bc7f653
Reviewed-on: https://go-review.googlesource.com/c/term/+/713420
Auto-Submit: Sean Liao <sean@liao.dev>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Sean Liao <sean@liao.dev>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

terminal.go

diff --git a/terminal.go b/terminal.go
index bddb2e2..9255449 100644
--- a/terminal.go
+++ b/terminal.go
@@ -413,7 +413,7 @@
 	}
 }
 
-// countToLeftWord returns then number of characters from the cursor to the
+// countToLeftWord returns the number of characters from the cursor to the
 // start of the previous word.
 func (t *Terminal) countToLeftWord() int {
 	if t.pos == 0 {
@@ -438,7 +438,7 @@
 	return t.pos - pos
 }
 
-// countToRightWord returns then number of characters from the cursor to the
+// countToRightWord returns the number of characters from the cursor to the
 // start of the next word.
 func (t *Terminal) countToRightWord() int {
 	pos := t.pos
@@ -478,7 +478,7 @@
 	return length
 }
 
-// histroryAt unlocks the terminal and relocks it while calling History.At.
+// historyAt unlocks the terminal and relocks it while calling History.At.
 func (t *Terminal) historyAt(idx int) (string, bool) {
 	t.lock.Unlock()     // Unlock to avoid deadlock if History methods use the output writer.
 	defer t.lock.Lock() // panic in At (or Len) protection.