fix missing dependency in an example (#343)

The focus-refetching example is missing the axios dependency in the
package.json, if we run the example locally there isn't any problem, but
if we use the codesandbox documentation link, the example is showing a
  problem with the missing dependency.

Author: juanprq

examples/focus-refetching/package.json

@@ -4,6 +4,7 @@
   "main": "index.js",
   "license": "MIT",
   "dependencies": {
+    "axios": "0.19.2",
     "isomorphic-unfetch": "3.0.0",
     "next": "9.3.2",
     "react": "16.13.0",

examples/focus-refetching/yarn.lock

@@ -1494,6 +1494,13 @@ autoprefixer@^9.6.1:
     postcss "^7.0.19"
     postcss-value-parser "^4.0.2"
 
+axios@0.19.2:
+  version "0.19.2"
+  resolved "https://registry.yarnpkg.com/axios/-/axios-0.19.2.tgz#3ea36c5d8818d0d5f8a8a97a6d36b86cdc00cb27"
+  integrity sha512-fjgm5MvRHLhx+osE2xoekY70AhARk3a6hkN+3Io1jc00jtquGvxYlKlsFUhmUET0V5te6CcZI7lcv2Ym61mjHA==
+  dependencies:
+    follow-redirects "1.5.10"
+
 babel-code-frame@^6.22.0:
   version "6.26.0"
   resolved "https://registry.yarnpkg.com/babel-code-frame/-/babel-code-frame-6.26.0.tgz#63fd43f7dc1e3bb7ce35947db8fe369a3f58c74b"
@@ -2286,6 +2293,13 @@ debug@2.6.9, debug@^2.2.0, debug@^2.3.3:
   dependencies:
     ms "2.0.0"
 
+debug@=3.1.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-3.1.0.tgz#5bb5a0672628b64149566ba16819e61518c67261"
+  integrity sha512-OX8XqP7/1a9cqkxYw2yXss15f26NKWBpDXQd0/uK/KPqdQhxbPa994hnzjcE2VqQpDslf55723cKPUOGSmMY3g==
+  dependencies:
+    ms "2.0.0"
+
 debug@^3.0.0, debug@^3.2.6:
   version "3.2.6"
   resolved "https://registry.yarnpkg.com/debug/-/debug-3.2.6.tgz#e83d17de16d8a7efb7717edbe5fb10135eee629b"
@@ -2798,6 +2812,13 @@ flush-write-stream@^1.0.0:
     inherits "^2.0.3"
     readable-stream "^2.3.6"
 
+follow-redirects@1.5.10:
+  version "1.5.10"
+  resolved "https://registry.yarnpkg.com/follow-redirects/-/follow-redirects-1.5.10.tgz#7b7a9f9aea2fdff36786a94ff643ed07f4ff5e2a"
+  integrity sha512-0V5l4Cizzvqt5D44aTXbFZz+FtyXV1vrDN6qrelxtfYQKW0KO0W2T/hkE8xvGa/540LkZlkaUjO4ailYTFtHVQ==
+  dependencies:
+    debug "=3.1.0"
+
 follow-redirects@^1.0.0:
   version "1.10.0"
   resolved "https://registry.yarnpkg.com/follow-redirects/-/follow-redirects-1.10.0.tgz#01f5263aee921c6a54fb91667f08f4155ce169eb"