Add some missing doc comments

As pointed out by the linter, some exported functions and types are
missing doc comments.
The linter warnings have been reduced from 194 to 116.
Not all missing comments have been added in this commit though.

1 files changed, 1 insertions, 0 deletions

diff --git a/tpl/template.go b/tpl/template.go
index 2ee322498..02d4a541c 100644
--- a/tpl/template.go
+++ b/tpl/template.go
@@ -101,6 +101,7 @@ func (t *TemplateAdapter) Tree() string {
 	return s
 }
 
+// TemplateFuncsGetter allows to get a map of functions.
 type TemplateFuncsGetter interface {
 	GetFuncs() map[string]interface{}
 }