document query features not currently shown

[tynanford]

@jeonghanlee found that you can use OR syntax to search for PV names:

LTB_*VVR*;LN_*VVR* (ok)
LTB_*VVR*|LN_*VVR* (ok)
LTB_*VVR*,LN_*VVR* (nok)

[jeonghanlee]

@tynanford Here are more examples.

[tynanford]

The comma not working is probably related to #96 which was my hack to get ALS PV names with commas working in pvinfo