Re: doc patch: clarify the naming rule for injection_points

Hi,

> Naming rule of points is not determined yet, but most of them have lower cases
> and each term are divided by dash "-". I think this is a good chance to formally
> clarify it. PSA adding the description.
>
> I was confused the correct place for the description. I added at the end of first
> paragraph, because it describes how we add and use it. Suggestions are very
> welcomed.

```
-     their own code using the same macro.
+     their own code using the same macro.  The name of injection points must be
+     lower characters, and dashes must separate its terms.
```

Perhaps "must" is a too strong statement. I suggest something like:

"""
By convention, the name of injection points ...
"""

I have mixed feelings about the patch overall though. This would mean
that we need to rename injection points like this:

``
AtEOXact_Inval-with-transInvalInfo
heap_update-before-pin
```

Otherwise we would contradict our own documentation.

I don't mind heap-update-before-pin, but not 100% sure if:

at-eo-xact-inval-with-trans-inval-info

... would be a better name than the current one.

--
Best regards,
Aleksander Alekseev