feat: add SendKey envvar config metadata (#1331)

## Which problem is this PR solving?

Add SendKey envvar to config metadata and generate docs

## Short description of the changes

- docs

config.md

@@ -1,7 +1,7 @@
 # Honeycomb Refinery Configuration Documentation
 
 This is the documentation for the configuration file for Honeycomb's Refinery.
-It was automatically generated on 2024-09-05 at 17:40:33 UTC.
+It was automatically generated on 2024-09-13 at 18:50:43 UTC.
 
 ## The Config file
 
@@ -178,14 +178,15 @@ This setting is applied **before** the `SendKey` and `SendKeyMode` settings.
 
 ### `SendKey`
 
-SendKey is an optional Honeycomb API key that Refinery can use to send data to Honeycomb, depending on configuration.
+SendKey is an optional Honeycomb API key that Refinery can use to send data to Honeycomb, depending on configuration. Setting this value via a command line flag may expose credentials - it is recommended to use the environment variable or a configuration file.
 
 If `SendKey` is set to a valid Honeycomb key, then Refinery can use the listed key to send data.
 The exact behavior depends on the value of `SendKeyMode`.
 
 - Eligible for live reload.
 - Type: `string`
 - Example: `SetThisToAHoneycombKey`
+- Environment variable: `REFINERY_SEND_KEY`
 
 ### `SendKeyMode`
 

config/metadata/configMeta.yaml

@@ -189,11 +189,13 @@ groups:
         valuetype: nondefault
         default: ""
         example: "SetThisToAHoneycombKey"
+        envvar: REFINERY_SEND_KEY
+        commandline: send-key
         reload: true
         validations:
           - type: format
             arg: apikeyOrBlank
-        summary: is an optional Honeycomb API key that Refinery can use to send data to Honeycomb, depending on configuration.
+        summary: is an optional Honeycomb API key that Refinery can use to send data to Honeycomb, depending on configuration. Setting this value via a command line flag may expose credentials - it is recommended to use the environment variable or a configuration file.
         description: >
           If `SendKey` is set to a valid Honeycomb key, then Refinery can use
           the listed key to send data.

config_complete.yaml

@@ -2,7 +2,7 @@
 ## Honeycomb Refinery Configuration ##
 ######################################
 #
-# created on 2024-09-05 at 17:40:32 UTC from ../../config.yaml using a template generated on 2024-09-05 at 17:40:29 UTC
+# created on 2024-09-13 at 18:50:42 UTC from ../../config.yaml using a template generated on 2024-09-13 at 18:50:40 UTC
 
 # This file contains a configuration for the Honeycomb Refinery. It is in YAML
 # format, organized into named groups, each of which contains a set of
@@ -162,7 +162,9 @@ AccessKeys:
     # AcceptOnlyListedKeys: false
 
     ## SendKey is an optional Honeycomb API key that Refinery can use to send
-    ## data to Honeycomb, depending on configuration.
+    ## data to Honeycomb, depending on configuration. Setting this value via
+    ## a command line flag may expose credentials - it is recommended to use
+    ## the environment variable or a configuration file.
     ##
     ## If `SendKey` is set to a valid Honeycomb key, then Refinery can use
     ## the listed key to send data. The exact behavior depends on the value

refinery_config.md

@@ -154,14 +154,15 @@ This setting is applied **before** the `SendKey` and `SendKeyMode` settings.
 
 ### `SendKey`
 
-`SendKey` is an optional Honeycomb API key that Refinery can use to send data to Honeycomb, depending on configuration.
+`SendKey` is an optional Honeycomb API key that Refinery can use to send data to Honeycomb, depending on configuration. Setting this value via a command line flag may expose credentials - it is recommended to use the environment variable or a configuration file.
 
 If `SendKey` is set to a valid Honeycomb key, then Refinery can use the listed key to send data.
 The exact behavior depends on the value of `SendKeyMode`.
 
 - Eligible for live reload.
 - Type: `string`
 - Example: `SetThisToAHoneycombKey`
+- Environment variable: `REFINERY_SEND_KEY`
 
 ### `SendKeyMode`
 

tools/convert/templates/configV2.tmpl

@@ -2,7 +2,7 @@
 ## Honeycomb Refinery Configuration ##
 ######################################
 #
-# created {{ now }} from {{ .Input }} using a template generated on 2024-09-05 at 17:40:29 UTC
+# created {{ now }} from {{ .Input }} using a template generated on 2024-09-13 at 18:50:40 UTC
 
 # This file contains a configuration for the Honeycomb Refinery. It is in YAML
 # format, organized into named groups, each of which contains a set of
@@ -161,7 +161,9 @@ AccessKeys:
     {{ conditional .Data "AcceptOnlyListedKeys" "nostar APIKeys" }}
 
     ## SendKey is an optional Honeycomb API key that Refinery can use to send
-    ## data to Honeycomb, depending on configuration.
+    ## data to Honeycomb, depending on configuration. Setting this value via
+    ## a command line flag may expose credentials - it is recommended to use
+    ## the environment variable or a configuration file.
     ##
     ## If `SendKey` is set to a valid Honeycomb key, then Refinery can use
     ## the listed key to send data. The exact behavior depends on the value