doc/index: document the correct way to spell coreboot

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I8e0c96dc4b68e60f9a36afb361c4d1c6f9742c31
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65772
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <patrick@coreboot.org>
diff --git a/Documentation/index.md b/Documentation/index.md
index ac90060..6692e3f 100644
--- a/Documentation/index.md
+++ b/Documentation/index.md
@@ -5,6 +5,11 @@
 [Documentation](https://review.coreboot.org/cgit/coreboot.git/tree/Documentation)
 directory in the source code.
 
+## Spelling of coreboot
+
+The correct spelling of coreboot is completely in lower case characters and in
+one word without a space between the two parts.
+
 ## Purpose of coreboot
 
 coreboot is a project to develop open source boot firmware for various