Apply batch of suggestions from code review

Co-authored-by: Michael Li <michael.li@hashicorp.com>

website/content/docs/configuration/controller.mdx

@@ -193,7 +193,7 @@ And optionally, a KMS stanza for configuration encryption purpose:
 # Configuration encryption block: decrypts sensitive values in the
 # configuration file. See `boundary config [encrypt|decrypt] -h`.
 kms "aead" {
-  purpose = "config"`
+  purpose = "config"
   aead_type = "aes-gcm"
   key = "7xtkEoS5EXPbgynwd+dDLHopaCqK8cq0Rpep4eooaTs="
 }
@@ -206,7 +206,7 @@ And optionally, a KMS stanza to enable the session recording feature:
 # of session recordings. If you do not add a BSR key to your
 # controller configuration, you cannot enable session recording.
 kms "aead" {
-  purpose = "bsr"`
+  purpose = "bsr"
   aead_type = "aes-gcm"
   key = "8Vg!XCbS.fzNKB@Uu.ccB588H#4iyHAd:TpgjuwC/;J;"
   key_id = "session_recording"
@@ -334,7 +334,7 @@ kms "aead" {
 # of session recordings. If you do not add a BSR key to your
 # controller configuration, you cannot enable session recording.
 kms "aead" {
-  purpose = "bsr"`
+  purpose = "bsr"
   aead_type = "aes-gcm"
   key = "8Vg!XCbS.fzNKB@Uu.ccB588H#4iyHAd:TpgjuwC/;J;"
   key_id = "session_recording"