Mass-replace blurb with seo:description in frontmatter

content/references/http-websocket-apis/public-api-methods/transaction-methods/submit.md

@@ -1,7 +1,8 @@
 ---
 html: submit.html
 parent: transaction-methods.html
-blurb: Send a transaction to the network.
+seo:
+    description: Send a transaction to the network.
 labels:
   - Transaction Sending
   - Payments

content/references/http-websocket-apis/public-api-methods/transaction-methods/submit_multisigned.md

@@ -1,7 +1,8 @@
 ---
 html: submit_multisigned.html
 parent: transaction-methods.html
-blurb: Send a multi-signed transaction to the network.
+seo:
+    description: Send a multi-signed transaction to the network.
 labels:
   - Transaction Sending
 ---

content/references/http-websocket-apis/public-api-methods/transaction-methods/transaction_entry.md

@@ -1,7 +1,8 @@
 ---
 html: transaction_entry.html
 parent: transaction-methods.html
-blurb: Retrieve info about a transaction from a particular ledger version.
+seo:
+    description: Retrieve info about a transaction from a particular ledger version.
 labels:
   - Transaction Sending
 ---

content/references/http-websocket-apis/public-api-methods/transaction-methods/tx.md

@@ -1,7 +1,8 @@
 ---
 html: tx.html
 parent: transaction-methods.html
-blurb: Retrieve info about a transaction from all the ledgers on hand.
+seo:
+    description: Retrieve info about a transaction from all the ledgers on hand.
 labels:
   - Transaction Sending
   - Payments

content/references/http-websocket-apis/public-api-methods/transaction-methods/tx_history.md

@@ -1,7 +1,8 @@
 ---
 html: tx_history.html
 parent: transaction-methods.html
-blurb: Retrieve info about all recent transactions.
+seo:
+    description: Retrieve info about all recent transactions.
 ---
 # tx_history
 [[Source]](https://github.com/XRPLF/rippled/blob/master/src/ripple/rpc/handlers/TxHistory.cpp "Source")