DynamicDiscovery - Guess num_oid if not provided in YAML file (#12570)

* Guess num_oid if not provided in YAML file
* Discover Processor num_oid if necessary
* num_oid is now optional

* documentation upgrade

doc/Developing/os/Health-Information.md

@@ -88,9 +88,9 @@ are as follows:
 - `oid` (required): This is the name of the table you want to do the snmp walk on.
 - `value` (optional): This is the key within the table that contains
   the value. If not provided willuse `oid`
-- `num_oid` (required): This is the numerical OID that contains
-  `value`. This should always include `{{ $index }}`.  snmptranslate
-  -On can help figure out the number.
+- `num_oid` (optional): If not provided, this parameter should be computed
+  automatically by discovery process. This is the numerical OID that contains
+  `value`. This should usually include `{{ $index }}`.
   In case the index is a string, `{{ $index_string }}` can be used instead.
 - `divisor` (optional): This is the divisor to use against the returned `value`.
 - `multiplier` (optional): This is the multiplier to use against the returned `value`.

doc/Developing/os/Mem-CPU-Information.md

@@ -115,7 +115,7 @@ Available yaml data keys:
 Key | Default | Description
 ----- | --- | -----
 oid | required | The string based oid to fetch data, could be a table or a single value
-num_oid | required | the numerical oid to fetch data from when polling, usually should be appended by {{ $index }}
+num_oid | optional | The numerical oid to fetch data from when polling, usually should be appended by {{ $index }}. Computed by discovery process if not provided.
 value | optional | Oid to retrieve data from, primarily used for tables
 precision | 1 | The multiplier to multiply the data by. If this is negative, the data will be multiplied then subtracted from 100.
 descr | Processor | Description of this processor, may be an oid or plain string.  Helpful values {{ $index }} and {{$count}}