[8.11] Document ways to provide multiple Agent uninstall tokens (back…

…port #6300) (#6357)

* Document ways to provide multiple Agent uninstall tokens (#6300)

* Document ways to provide multiple Agent uninstall tokens

* Apply suggestions from code review

Co-authored-by: Benjamin Ironside Goldstein <91905639+benironside@users.noreply.github.com>

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Co-authored-by: Benjamin Ironside Goldstein <91905639+benironside@users.noreply.github.com>
(cherry picked from commit 87e3acb)

# Conflicts:
#	docs/getting-started/uninstall-agent.asciidoc
#	docs/serverless/edr-install-config/agent-tamper-protection.asciidoc
#	docs/serverless/edr-install-config/uninstall-agent.asciidoc

* Delete docs/serverless directory and its contents

* Resolves conflict

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Co-authored-by: natasha-moore-elastic <137783811+natasha-moore-elastic@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: natasha-moore-elastic <natasha.moore@elastic.co>

docs/getting-started/agent-tamper-protection.asciidoc

@@ -47,3 +47,5 @@ If you need the uninstall token to remove {agent} from an endpoint, you can find
 
 ** Click the *Show token* icon in the *Token* column to reveal a specific token.
 ** Click the *View uninstall command* icon in the *Actions* column to open the *Uninstall agent* flyout, containing the full uninstall command with the token.
+
+TIP: If you have many tamper-protected {agent} policies, you may want to <<multiple-uninstall-tokens>> in a single command.

docs/getting-started/uninstall-agent.asciidoc

@@ -11,3 +11,33 @@ For example, to uninstall {agent} on a macOS or Linux host:
 ----------------------------------
 sudo elastic-agent uninstall --uninstall-token 12345678901234567890123456789012
 ----------------------------------
+
+[discrete]
+[[multiple-uninstall-tokens]]
+== Provide multiple uninstall tokens
+
+If you have multiple tamper-protected {agent} policies, you may want to provide multiple uninstall tokens in a single command. There are two ways to do this:
+
+* The `--uninstall-token` command can receive multiple uninstall tokens separated by a comma, without spaces.
++
+[source,shell]
+----------------------------------
+sudo elastic-agent uninstall -f --uninstall-token 7b3d364db8e0deb1cda696ae85e42644,a7336b71e243e7c92d9504b04a774266
+----------------------------------
+
+* `--uninstall-token`'s argument can also be a path to a text file with one uninstall token per line. 
++
+NOTE: You must use the full file path, otherwise the file may not be found.
++
+[source,shell]
+----------------------------------
+sudo elastic-agent uninstall -f --uninstall-token /tmp/tokens.txt
+----------------------------------
++
+In this example, `tokens.txt` would contain:
++
+[source,txt]
+----------------------------------
+7b3d364db8e0deb1cda696ae85e42644
+a7336b71e243e7c92d9504b04a774266
+----------------------------------