docs: use code instead of shell (#46341)

Co-authored-by: Steven Martin <[email protected]>

docs/pages/admin-guides/infrastructure-as-code/teleport-operator.mdx

@@ -170,7 +170,7 @@ For example the command:
 $ kubectl explain teleportroles.spec
 ```
 Returns the following fields:
-```shell
+```code
 KIND:     TeleportRole
 VERSION:  resources.teleport.dev/v5
 
@@ -231,7 +231,7 @@ Here `SuccessfullyReconciled` is `False` and the error is `role my-non-existing-
 
 If the status is not present or does not give sufficient information to solve the issue, check the operator logs:
 
-```shell
+```code
 $ kubectl logs "$AUTH_POD" -c operator
 ```
 

docs/pages/enroll-resources/database-access/auto-user-provisioning/mysql.mdx

@@ -107,7 +107,7 @@ granted through database-specific roles, such as `reader`.
 
 Otherwise you may see errors like the following:
 
-```shell
+```code
 $ tsh db connect --db-name <database> example
 ERROR 1105 (HY000): ERROR 1044 (42000): Access denied for user '<your-teleport-username>'@'%' to database '<database>'
 ```
@@ -116,7 +116,7 @@ ERROR 1105 (HY000): ERROR 1044 (42000): Access denied for user '<your-teleport-u
 
 You may encounter the following error when connecting to an AWS RDS Aurora
 reader endpoint:
-```shell
+```code
 $ tsh db connect --db-name <database> example
 ERROR 3501 (HY000): The ACL operation failed due to the following error from SE: errcode 165 - Table is read only
 ```

docs/pages/enroll-resources/database-access/auto-user-provisioning/postgres.mdx

@@ -100,7 +100,7 @@ You may encounter the following error when the admin user or the roles assigned
 to the auto-provisioned user do not have permission to connect to the target
 database:
 
-```shell
+```code
 $ tsh db connect --db-name <database> example
 ...
 FATAL: permission denied for database "<database>"
@@ -117,7 +117,7 @@ GRANT CONNECT ON DATABASE <database> to "reader";
 
 You may encounter the following error when connecting to an AWS RDS Aurora
 reader endpoint:
-```shell
+```code
 $ tsh db connect --db-name <database> example
 psql: error: connection to server at "localhost" (::1), port 12345 failed: Connection refused
 ...
@@ -131,7 +131,7 @@ endpoints. Please use auto-user provisioning on the primary endpoints.
 
 You may encounter the following error when connecting if the admin user does
 not have `USAGE` permission on the schema:
-```shell
+```code
 $ tsh db connect --db-name <database> example
 psql: error: connection to server at "localhost" (::1), port 12345 failed: Connection refused
 ...
@@ -148,7 +148,7 @@ GRANT CREATE ON SCHEMA public TO "teleport-admin";
 ### Permission denied to grant role "rds_iam"
 
 You may encounter the following error when connecting to an RDS database:
-```shell
+```code
 $ tsh db connect --db-name <database> example
 psql: error: connection to server at "localhost" (::1), port 12345 failed: Connection refused
 ...

docs/pages/includes/database-access/auto-user-provisioning/troubleshooting-remote-username.mdx

@@ -1,6 +1,6 @@
 You may encounter the following error when connecting to a database in a remote
 cluster:
-```shell
+```code
 > tsh db connect --db-name <database> example
 ERROR: please use your mapped remote username ("remote-<your-teleport-username>-<root-cluster-name>") to connect instead of "<database-user>"
 ```

docs/pages/includes/database-access/redis-create-users.mdx

@@ -1,6 +1,6 @@
 Each Redis user must be protected by a strong password. We recommend using OpenSSL to generate passwords:
 
-```shell
+```code
 openssl rand -hex 32
 ```
 
@@ -17,7 +17,7 @@ and sets of ACL rules. Redis allows you to provide passwords in plaintext or an
 We strongly recommend using an SHA256 hash instead of plaintext passwords.
 
 You can use the command below to generate an SHA256 hash from a password.
-```shell
+```code
 echo -n STRONG_GENERATED_PASSWORD | sha256sum
 ```
 

docs/pages/reference/helm-reference/teleport-cluster.mdx

@@ -1329,7 +1329,7 @@ set to use a TLS certificate issued by a trusted internal CA rather than a publi
 
 You should create the secret in the same namespace as Teleport using a command like this:
 
-```shell
+```code
 kubectl create secret tls my-tls-secret --cert=/path/to/cert/file --key=/path/to/key/file
 ```
 
@@ -1359,7 +1359,7 @@ in the pod logs.
 
 You should create the secret in the same namespace as Teleport using a command like this:
 
-```shell
+```code
 kubectl create secret generic my-root-ca --from-file=ca.pem=/path/to/root-ca.pem
 ```
 

docs/pages/reference/join-methods.mdx

@@ -241,7 +241,7 @@ They are time-bound and are typically created just before joining an instance to
 the Teleport cluster.
 
 They can be created by the CLI (a strong random value is picked when not specified, default TTL is 30 minutes):
-```shell
+```code
 $ tctl tokens add --type discovery,app --ttl 15m
 ```