fix(DOC-1940): clarify rpk topic consume keeps connection open

modules/reference/pages/rpk/rpk-topic/rpk-topic-consume.adoc

@@ -7,8 +7,13 @@ Consuming records reads from any amount of input topics, formats each record
 according to `--format`, and prints them to `STDOUT`. The output formatter
 understands a wide variety of formats.
 
-The default output format `--format json` is a special format that outputs each
-record as JSON.
+By default, `rpk topic consume` opens a persistent connection and waits
+indefinitely for new records to arrive. It does not exit after consuming
+existing records. To stop consuming, press kbd:[Ctrl+C], or use `--num` to exit
+after a fixed number of records, or specify an end offset with `--offset`
+(for example, `-o :end`).
+
+`--format json` is the default, and outputs each record as a JSON object.
 
 include::reference:partial$topic-format.adoc[]
 
@@ -82,7 +87,7 @@ specification, similar to timestamps above.
 
 Unpacking text can allow translating binary input into readable output. If a
 value is a big-endian uint32, `%v` prints the raw four bytes, while
-`%v{unpack[>I]}` prints the number in as ASCII. If unpacking exhausts the
+`%v{unpack[>I]}` prints the number as ASCII. If unpacking exhausts the
 input before something is unpacked fully, an error message is appended to the
 output.
 
@@ -103,7 +108,7 @@ of the above rules about `%K`, `%V`, text, and numbers apply.
 
 Values for consumed records can be omitted by using the `--meta-only` flag.
 
-Tombstone records (records with a `null` value) have their value omitted from the JSON output by default. All other records, including those with an empty-string value (`""`), will have their values printed.
+Tombstone records (records with a `null` value) have their value omitted from the JSON output by default. All other records, including those with an empty-string value (`""`), have their values printed.
 
 == Offsets