util: change coreboot to lowercase

The word 'coreboot' should always be written in lowercase, even at the
start of a sentence.

Change-Id: I0a024d82d331c0794fe087e440b4e1924129a13c
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20030
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/hugo/config.toml

@@ -6,7 +6,7 @@ metadataformat = "yaml"
 canonifyurls = true
 
 [params]
-  provider = "Coreboot"
+  provider = "coreboot"
   repo_url = "https://review.coreboot.org/cgit/coreboot.git"
   logo = "images/coreboot.svg"
   favicon = "images/favicon.png"