docs/INSTALL.md: add list of build tags

This adds a list of tags that can be used when building or installing
lnd from source. Links to relevant code, protobuf definitions, or
documentation are included to illustrate the purpose of each tag.

Closes #3598.

docs/INSTALL.md

@@ -238,6 +238,32 @@ used directly:
 ⛰  go install -v ./...
 ```
 
+**Tags**
+
+Release binaries and installations from source using `make release-install`
+will have the following tags:
+
+- [autopilotrpc](/lnrpc/autopilotrpc/autopilot.proto)
+- [signrpc](/lnrpc/signrpc/signer.proto)
+- [walletrpc](/lnrpc/walletrpc/walletkit.proto)
+- [chainrpc](/lnrpc/chainrpc/chainnotifier.proto)
+- [invoicesrpc](/lnrpc/invoicesrpc/invoices.proto)
+- [routerrpc](/lnrpc/routerrpc/router.proto)
+- [watchtowerrpc](/lnrpc/watchtowerrpc/watchtower.proto)
+- [monitoring](/monitoring) (for Prometheus integration)
+- [peersrpc](/lnrpc/peersrpc/peers.proto)
+- [kvdb_postrgres](/docs/postgres.md)
+- [kvdb_etcd](/docs/etcd.md)
+
+The `dev` tag is used for development builds, and is not included in the
+release builds & installation.
+
+You can specify a custom set of tags when installing from source using the `tags=""` parameter. For example:
+
+```shell
+make install tags="signrpc walletrpc routerrpc invoicesrpc"
+```
+
 **Updating**
 
 To update your version of `lnd` to the latest version run the following