Update bios for former members

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <[email protected]>

Author: alexellis

_staff_members/burton.md

@@ -5,5 +5,5 @@ image_path: /images/author/burton.png
 twitter_username: _burtonr
 github_username: burtonr
 webpage: https://burtonr.dev/
-blurb: Contributor <a href="https://twitter.com/openfaas">@openfaas</a>. Software Principal Engineer <a href="https://www.delltechnologies.com">@Dell Technologies</a>
+blurb: Former Core Team. Software Principal Engineer <a href="https://www.delltechnologies.com">@Dell Technologies</a>
 ---

_staff_members/ed.md

@@ -6,5 +6,5 @@ twitter_username: ewilde
 github_username: ewilde
 linkedin_username: ewilde
 webpage: http://blogs.edwardwilde.com/
-blurb: Contributor <a href="https://twitter.com/openfaas">@openfaas</a>. Platform architect <a href="https://form3.tech">@f3fincloud</a>
+blurb: Former Core Team. Platform architect <a href="https://form3.tech">@f3fincloud</a>
 ---

_staff_members/john.md

@@ -5,5 +5,5 @@ image_path: /images/author/john.png
 twitter_username: mccabejohn
 github_username: johnmccabe
 webpage: https://johnmccabe.net
-blurb: Contributor <a href="https://twitter.com/openfaas">@openfaas</a>. Staff Engineer at Proofpoint
+blurb: Former Core Team. Staff Engineer at Proofpoint
 ---

_staff_members/ken.md

@@ -5,5 +5,5 @@ image_path: /images/author/ken.png
 twitter_username: kenfdev
 github_username: kenfdev
 webpage: http://kenev.net/
-blurb: Software Engineer at CYDAS Inc.
+blurb: Former Members team. Software Engineer at Sansan.
 ---

_staff_members/stefan.md

@@ -5,5 +5,5 @@ image_path: /images/author/stefan.png
 twitter_username: stefanprodan
 github_username: stefanprodan
 webpage: https://stefanprodan.com/
-blurb: Members Team <a href="https://twitter.com/openfaas">@openfaas</a>. DX Engineer <a href="https://twitter.com/weaveworks">@weaveworks</a>.
+blurb: Former Core team. DX Engineer <a href="https://twitter.com/weaveworks">@weaveworks</a>.
 ---