doc: remove Chris Dickinson from active releasers

The last release Chris did was v1.8.1 from April 2015.

PR-URL: #11011
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>

README.md

@@ -350,8 +350,6 @@ project.
 
 Releases of Node.js and io.js will be signed with one of the following GPG keys:
 
-* **Chris Dickinson** <christopher.s.dickinson@gmail.com>
-`9554F04D7259F04124DE6B476D5A82AC7E37093B`
 * **Colin Ihrig** <cjihrig@gmail.com>
 `94AE36675C464D64BAFA68DD7434390BDBE9B9C5`
 * **Evan Lucas** <evanlucas@me.com>
@@ -368,7 +366,6 @@ Releases of Node.js and io.js will be signed with one of the following GPG keys:
 The full set of trusted release keys can be imported by running:
 
 ```shell
-gpg --keyserver pool.sks-keyservers.net --recv-keys 9554F04D7259F04124DE6B476D5A82AC7E37093B
 gpg --keyserver pool.sks-keyservers.net --recv-keys 94AE36675C464D64BAFA68DD7434390BDBE9B9C5
 gpg --keyserver pool.sks-keyservers.net --recv-keys FD3A5288F042B6850C66B31F09FE44734EB7990E
 gpg --keyserver pool.sks-keyservers.net --recv-keys 71DCFD284A79C3B38668286BC97EC7A07EDE3FC1
@@ -383,6 +380,8 @@ on what to do with these keys to verify that a downloaded file is official.
 Previous releases of Node.js have been signed with one of the following GPG
 keys:
 
+* **Chris Dickinson** <christopher.s.dickinson@gmail.com>
+`9554F04D7259F04124DE6B476D5A82AC7E37093B`
 * **Isaac Z. Schlueter** <i@izs.me>
 `93C7E9E91B49E432C2F75674B0A78B0A6C481CF6`
 * **Julien Gilli** <jgilli@fastmail.fm>