Update flags in usage.md (#1123)

docs/usage.md

@@ -12,6 +12,7 @@ Flags:
       --oidc-client-secret string                       Client secret of the provider
       --oidc-extra-scope strings                        Scopes to request to the provider
       --oidc-use-pkce                                   Force PKCE usage
+      --oidc-use-access-token                           Instead of using the id_token, use the access_token to authenticate to Kubernetes
       --token-cache-dir string                          Path to a directory for token cache (default "~/.kube/cache/oidc-login")
       --force-refresh                                   If set, refresh the ID token regardless of its expiration time
       --certificate-authority stringArray               Path to a cert file for the certificate authority
@@ -36,16 +37,16 @@ Flags:
 
 Global Flags:
       --add_dir_header                   If true, adds the file directory to the header of the log messages
-      --alsologtostderr                  log to standard error as well as files
+      --alsologtostderr                  log to standard error as well as files (no effect when -logtostderr=true)
       --log_backtrace_at traceLocation   when logging hits line file:N, emit a stack trace (default :0)
-      --log_dir string                   If non-empty, write log files in this directory
-      --log_file string                  If non-empty, use this log file
-      --log_file_max_size uint           Defines the maximum size a log file can grow to. Unit is megabytes. If the value is 0, the maximum file size is unlimited. (default 1800)
+      --log_dir string                   If non-empty, write log files in this directory (no effect when -logtostderr=true)
+      --log_file string                  If non-empty, use this log file (no effect when -logtostderr=true)
+      --log_file_max_size uint           Defines the maximum size a log file can grow to (no effect when -logtostderr=true). Unit is megabytes. If the value is 0, the maximum file size is unlimited. (default 1800)
       --logtostderr                      log to standard error instead of files (default true)
-      --one_output                       If true, only write logs to their native severity level (vs also writing to each lower severity level)
+      --one_output                       If true, only write logs to their native severity level (vs also writing to each lower severity level; no effect when -logtostderr=true)
       --skip_headers                     If true, avoid header prefixes in the log messages
-      --skip_log_headers                 If true, avoid headers when opening log files
-      --stderrthreshold severity         logs at or above this threshold go to stderr (default 2)
+      --skip_log_headers                 If true, avoid headers when opening log files (no effect when -logtostderr=true)
+      --stderrthreshold severity         logs at or above this threshold go to stderr when writing to files and stderr (no effect when -logtostderr=true or -alsologtostderr=true) (default 2)
   -v, --v Level                          number for the log level verbosity
       --vmodule moduleSpec               comma-separated list of pattern=N settings for file-filtered logging
 ```