Documentation: Adjust master -> main branch

Some of our documentation still points to the wrong branches

Change-Id: Idb72e4f44f294f64eb01c588027d300a53d6fb41
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77875
Reviewed-by: Patrick Georgi <patrick@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

Documentation/infrastructure/builders.md

@@ -74,7 +74,7 @@ These times are taken from the week of Feb 21 - Feb 28, 2022
 
 There are a number of builds handled by the coreboot jenkins builders,
 for a number of different projects - coreboot, flashrom, memtest86+,
-em100, etc.  Many of these have builders for their current master branch
+em100, etc.  Many of these have builders for their current main branch
 as well as Gerrit and [Coverity](coverity.md) builds.
 
 
@@ -91,14 +91,14 @@ machines.  These tasks run overnight in the US timezones.
 You can see all the builds in the main jenkins interface:
 [https://qa.coreboot.org/](https://qa.coreboot.org/)
 
-Most of the time on the builders is taken up by the coreboot master and
+Most of the time on the builders is taken up by the coreboot main and
 coreboot gerrit builds.
 
 * [coreboot gerrit build](https://qa.coreboot.org/job/coreboot-gerrit/)
 ([Time trend](https://qa.coreboot.org/job/coreboot-gerrit/buildTimeTrend))
 
 
-* [coreboot master build](https://qa.coreboot.org/job/coreboot/)
+* [coreboot main build](https://qa.coreboot.org/job/coreboot/)
  ([Time trend](https://qa.coreboot.org/job/coreboot/buildTimeTrend))