DOC: fix some spelling issues over multiple files
This is from the output of codespell and may be backported.
diff --git a/BRANCHES b/BRANCHES
index 6cb275c..53b2ee9 100644
--- a/BRANCHES
+++ b/BRANCHES
@@ -134,7 +134,7 @@
Branches up to 1.8 are all designated as "long-term supported" ("LTS" for
short), which means that they are maintained for several years after the
release. These branches were emitted at a pace of one per year since 1.5 in
-2014. As of 2019, 1.5 is still supported and widely used, eventhough it very
+2014. As of 2019, 1.5 is still supported and widely used, even though it very
rarely receives updates. After a few years these LTS branches enter a
"critical fixes only" status, which means that they will rarely receive a fix
but if that a critital issue affects them, a release will be made, with or