README.md: add project introduction paragraph

We want to present some information about the Oniro project and mention
the trademark. This was requested by project management.

Related-To: https://booting.oniroproject.org/distro/infra/-/issues/18


Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@huawei.com>

README.md

@@ -6,6 +6,21 @@ SPDX-License-Identifier: CC-BY-4.0
 
 # Oniro Project
 
+Welcome to the Oniro Project bootstrap git repository! You are welcome to take
+a tour and play with Oniro's initial code contribution in its final steps
+toward becoming the project's official code base. And, if you feel like
+joining, we would love to welcome you among the list of Oniro's initiating
+supporters. These are exciting times! There couldn't be a better moment for
+joining Oniro!
+
+Learn more about the [Oniro Project](https://oniroproject.org/).
+
+Read the [documentation](https://docs.oniroproject.org/).
+
+*\*Oniro is a trademark of Eclipse Foundation.*
+
+# About
+
 The **oniro** repository is a collection of bitbake layers that implement the
 build system support in Oniro Project. Check the `README.md` file in each of
 the included layers for layer-specific additional information.