The release files are tarballs of an install tree. So there is no install process. You just untar the release where ever you want it, and then run it from there.
As for docs, the toolchain works the same as any other GNU toolchain. The qemu works the same as any other qemu. I see that it only has system qemu, so this is for running bare metal programs. OpenOCD is for bare metal debugging and works basically the same as any other openocd release. You can use openocd with a target board and gdb to do jtag debugging. It can also be used with spike.
The spike-disassembler is the only cryptic looking one. This is a tool for taking verilator output and disassembling the instruction info inside the verilator trace logs. This is only useful if you have verilog for a core, and are using verilator to simulate it.
You should be able to find tutorials on how to use this stuff. You might find docs in the software source trees. But if you want something better, you might try looking at the eclipse package which has all of this stuff integrated together and might be easier to use. I don’t use eclipse myself though so can’t answer questions about it.
Here is a tutorial that talks about how some of this stuff works.