SDK: "Installer" component: improve statement regarding overlap with IDE

Current formulation of SDK proposal https://github.com/openhwgroup/core-v-docs/blob/master/program/Project%20Descriptions%20and%20Plans/SDK/sdk-project-concept.md "There wil be be some overlap with the IDE component, since Eclipse CDT has its own installer." sounds a bit fuzzy.

1. Eclipse CDT "per se" has no installer
2. There is a package "Eclipse IDE for C/C++ Developers" that has Eclipse Oomph installer
3. There is a package "Eclipse IDE for Embedded C/C++ Developers" that has Eclipse Oomph installer
4. There is a CORE-V IDE distribution that contains features from 2) and 3) and does not have a configuration for Eclipse Oomph installer yet
5. We are falling back to issue #459 since we should talk about "package manager"

Although Eclipse ecosystem has enough building blocks to fulfill install/update experience for both UI and headless components I must mention the technologies provided by PlatformIO that already supports "out-of-the-box" experience for embedded development.