Replace "function" with "command" in several user-facing doc (#15129)

crates/nu-std/std/log/mod.nu

@@ -77,7 +77,6 @@ def log-types [] {
     )
 }
 
-
 def parse-string-level [
     level: string
 ] {
@@ -96,7 +95,6 @@ def parse-string-level [
     }
 }
 
-
 def parse-int-level [
     level: int,
     --short (-s)
@@ -320,6 +318,6 @@ def "nu-complete log-level" [] {
 
 # Change logging level
 export def --env set-level [level: int@"nu-complete log-level"] {
-    # Keep it as a string so it  can be passed to child processes
+    # Keep it as a string so it can be passed to child processes
     $env.NU_LOG_LEVEL = $level | into string
 }