add golangci-lint errcheck warning

we were getting this warning:

```
WARN [config_reader] The configuration option `linters.errcheck.exclude`
is deprecated, please use `linters.errcheck.exclude-functions`.
```

so removing .errcheck.txt and adding the functions to the .golangci.yml

add a comment to the go code to explain what the function does and
launch golangci-lint to make sure it's all good.

Signed-off-by: Chmouel Boudjnah <[email protected]>

Author: chmouel

.errcheck.txt

@@ -15,7 +15,14 @@ linters-settings:
     disabled-checks:
       - unlambda
   errcheck:
-    exclude: .errcheck.txt
+    exclude-functions:
+      - (*github.com/tektoncd/pipeline/vendor/go.uber.org/zap.SugaredLogger).Sync
+      - flag.Set
+      - logger.Sync
+      - fmt.Fprintf
+      - fmt.Fprintln
+      - (io.Closer).Close
+      - updateConfigMap
   gofumpt:
     extra-rules: true
 linters:

.golangci.yml

@@ -21,7 +21,33 @@ var (
 	mapType    = reflect.TypeOf(&structpb.Struct{})
 )
 
-// ReplacePlaceHoldersVariables Replace those {{var}} placeholders to the runinfo variable.
+// ReplacePlaceHoldersVariables is a function that replaces placeholders in a
+// given string template with their corresponding values. The placeholders are
+// expected to be in the format `{{key}}`, where `key` is the identifier for a
+// value.
+//
+// The function first checks if the key in the placeholder has a prefix of
+// "body", "headers", or "files". If it does and both `rawEvent` and `headers`
+// are not nil, it attempts to retrieve the value for the key using the
+// `customparams.CelValue` function and returns the corresponding string
+// representation. If the key does not have any of the mentioned prefixes, the
+// function checks if the key exists in the `dico` map. If it does, the
+// function replaces the placeholder with the corresponding value from the
+// `dico` map.
+//
+// Parameters:
+//   - template (string): The input string that may contain placeholders in the
+//     format `{{key}}`.
+//   - dico (map[string]string): A dictionary mapping keys to their corresponding
+//     string values. If a placeholder's key is found in this dictionary, it will
+//     be replaced with the corresponding value.
+//   - rawEvent (any): The raw event data that may be used to retrieve values for
+//     placeholders with keys that have a prefix of "body", "headers", or "files".
+//   - headers (http.Header): The HTTP headers that may be used to retrieve
+//     values for placeholders with keys that have a prefix of "headers".
+//   - changedFiles (map[string]interface{}): A map of changed files that may be
+//     used to retrieve values for placeholders with keys that have a prefix of
+//     "files".
 func ReplacePlaceHoldersVariables(template string, dico map[string]string, rawEvent any, headers http.Header, changedFiles map[string]interface{}) string {
 	return keys.ParamsRe.ReplaceAllStringFunc(template, func(s string) string {
 		parts := keys.ParamsRe.FindStringSubmatch(s)