docs: updated info to find FTB identifiers (#1386)

Fixes #612

README.md

@@ -614,8 +614,8 @@ Crucible is only available for 1.7.10, so be sure to set `VERSION=1.7.10`.
 [Feed the Beast application](https://www.feed-the-beast.com/) modpacks are supported by using `-e TYPE=FTBA` (**note** the "A" at the end of the type). This server type will automatically take care of downloading and installing the modpack and appropriate version of Forge, so the `VERSION` does not need to be specified.
 
 ### Environment Variables:
-- `FTB_MODPACK_ID`: **required**, the numerical ID of the modpack to install. The ID can be located by [finding the modpack](https://www.feed-the-beast.com/modpack) and using the "ID" displayed next to the name
-- `FTB_MODPACK_VERSION_ID`: optional, the numerical Id of the version to install. If not specified, the latest version will be installed. The "Version ID" can be obtained by drilling into the Versions tab and clicking a specific version.
+- `FTB_MODPACK_ID`: **required**, the numerical ID of the modpack to install. The ID can be located by [finding the modpack](https://www.feed-the-beast.com/modpack) and hovering over the name of the modpack, [as shown here](docs/ftba-identifier-popup.png).
+- `FTB_MODPACK_VERSION_ID`: optional, the numerical Id of the version to install. If not specified, the latest version will be installed. The "Version ID" can be obtained by drilling into the Versions tab and hovering over the version name, [as shown here](docs/ftba-version-id-popup.png).
 
 ### Upgrading