[PATCH] doc: document telemetry command name restrictions

[Sivaprasad Tummala <sivaprasad.tummala@amd.com>]

Telemetry command names must contain only alphanumeric characters
(`A-Z`, `a-z`, `0-9`), underscore (`_`), and forward slash (`/`).
Other characters, including hyphens (`-`), are not allowed and
cause registration to fail.

This patch updates the documentation to explicitly state these
restrictions and highlights the existing invalid example
"/l3fwd-power/stats" (in l3fwd-power app).

Signed-off-by: Sivaprasad Tummala <sivaprasad.tummala@amd.com>
---
 doc/guides/prog_guide/telemetry_lib.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/doc/guides/prog_guide/telemetry_lib.rst b/doc/guides/prog_guide/telemetry_lib.rst
index 32f525a67f..6ae5067474 100644
--- a/doc/guides/prog_guide/telemetry_lib.rst
+++ b/doc/guides/prog_guide/telemetry_lib.rst
@@ -157,6 +157,10 @@ command. An example command being registered is shown below:
     rte_telemetry_register_cmd("/example_lib/string_example", handle_string,
             "Returns an example string. Takes no parameters");
 
+The command name **must consist only of alphanumeric characters (`A-Z`, `a-z`,
+`0-9`) and the special characters underscore (`_`) and forward slash (`/`)**.
+Any other characters, including spaces, are not permitted and will cause the
+command registration to fail.
 
 Using Commands
 --------------
-- 
2.43.0