Re-levelization: move non-docs content, rename content→docs

For better URLs, the content folder has been renamed 'docs' and all
other files have been moved up a level. Also, non-docs images have been
moved to the static folder at the top level where they belong.

Many relative paths had to be fixed to make this work.

docs/references/protocol/transactions/index.md

@@ -10,7 +10,7 @@ metadata:
 
 A _Transaction_ is the only way to cause changes in the XRP Ledger. Transactions' outcomes are only [final](../../../concepts/transactions/finality-of-results/index.md) if signed, submitted, and accepted into a validated ledger version following the [consensus process](../../../concepts/consensus-protocol/index.md). Some ledger rules also generate _[pseudo-transactions](pseudo-transaction-types/pseudo-transaction-types.md)_, which aren't signed or submitted, but still must be accepted by consensus. Transactions that fail are also included in ledgers because they modify balances of XRP to pay for the anti-spam [transaction cost][].
 
-{% raw-partial file="/_snippets/common-links.md" /%}
+{% raw-partial file="/docs/_snippets/common-links.md" /%}
 
 
 {% child-pages /%}