[#453] Add documentation for rollup node service

docs/tx_rollup.md

@@ -0,0 +1,29 @@
+<!--
+   - SPDX-FileCopyrightText: 2022 Oxhead Alpha
+   - SPDX-License-Identifier: LicenseRef-MIT-OA
+   -->
+
+# Setting up transaction rollup node on Ubuntu
+
+`proto` variable can hold every active protocol, currently `013-PtJakart` and `014-PtKathma`.
+
+By default, `tezos-tx-rollup-node-$proto.service` will using:
+* `/var/lib/tezos/.tezos-client` as the `tezos-client` data directory, set in `DATA_DIR`
+* `http://localhost:8732` as the `tezos-node` RPC address, set in `NODE_RPC_ENDPOINT`
+* `127.0.0.1:8472` as the `tezos-tx-rollup-node-$proto` RPC address, set in `ROLLUP_NODE_RPC_ENDPOINT`
+* `observer` as the `tezos-tx-rollup-node-$proto` working mode, set in `MODE`
+* `rollup` as the rollup alias, set in `ROLLUP_ALIAS`
+
+In order to change defaults, edit `/etc/default/tezos-tx-rollup-node-$proto` file.
+
+At first you should originate rollup with the provided alias for some implicit account:
+```
+tezos-client originate tx rollup ${ROLLUP_ALIAS} from ${IMPLICIT_ACCOUNT_ALIAS}
+```
+
+After that, with the active `tezos-node` service available with the provided uri, run the following command
+```
+sudo systemctl start tezos-tx-rollup-node-$proto.service
+```
+
+For futher details, see [documentation](https://gitlab.com/tezos/tezos/-/blob/master/docs/jakarta/transaction_rollups.rst).