#69 Update instructions on the wiki to indicate that git-annex version should be smaller than 8

From here it seems that gin will not support git-annex whose version is larger than 8: https://github.com/G-Node/gin-cli/issues/319 Maybe this section of the documentation can be updated to reflect this? https://gin.g-node.org/G-Node/Info/wiki/GIN+CLI+Setup#binary-client-only

The [GIN client](https://gin.g-node.org/G-Node/Info/wiki/GIN+CLI+Setup#binary-client-only) should work with any git-annex version (>6) you have installed. The [Debian package](https://gin.g-node.org/G-Node/Info/wiki/GIN+CLI+Setup#bundle) includes git-annex version 8, which will not work with git-annex version 10 repos. We'll update the documentation to clarify this.