fix two typos in root files

Found while reading those introductory files. They weren't caught by
misspell, for some reason.

Change-Id: Ia90db9e6d131683a3813eaa98bd70cb50db0279d
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/238044
Reviewed-by: Julie Qiu <julie@golang.org>

README.md

@@ -47,7 +47,7 @@ the [known issues](https://github.com/golang/go/labels/go.dev) to see if your
 issue is already being discussed. If an issue does not already exist, feel free
 to [file an issue](https://golang.org/s/discovery-feedback).
 
-For answers to freqently asked questions, see [go.dev](https://go.dev/about).
+For answers to frequently asked questions, see [go.dev](https://go.dev/about).
 
 You can also chat with us on the #tools slack channel on the
 [Gophers slack](https://invite.slack.golangbridge.org).

all.bash

@@ -28,7 +28,7 @@ verify_header() {
     for FILE in $@
     do
         # Allow for the copyright header to start on either of the first two
-        # lines, to accomodate conventions for CSS and HTML.
+        # lines, to accommodate conventions for CSS and HTML.
         line="$(head -3 $FILE)"
         if [[ ! $line == *"The Go Authors. All rights reserved."* ]] &&
          [[ ! $line == "// DO NOT EDIT. This file was copied from" ]]; then