Updating Flex manual for LLD and liquid classes

docs/flex-manual/docs/protocol-development.md

@@ -367,7 +367,7 @@ Python protocols generally follow the same basic structure:
 
     - Locations of [modules](https://docs.opentrons.com/v2/new_modules.html), [labware](https://docs.opentrons.com/v2/new_labware.html), and [deck fixtures](https://docs.opentrons.com/v2/deck_slots.html#deck-configuration).
 
-    - [Liquid](https://docs.opentrons.com/v2/new_labware.html#labeling-liquids-in-wells) types and locations (optional).
+    - Liquid [classes](https://docs.opentrons.com/v2/liquid_classes) or [types and locations](https://docs.opentrons.com/v2/new_labware.html#labeling-liquids-in-wells) (optional).
 
     - Commands the system will physically execute (e.g., [simple](https://docs.opentrons.com/v2/new_atomic_commands.html) or [complex](https://docs.opentrons.com/v2/new_complex_commands.html) liquid
       handling commands, [module](https://docs.opentrons.com/v2/new_modules.html) commands, or [movement](https://docs.opentrons.com/v2/robot_position.html) commands).
@@ -433,6 +433,10 @@ Some module commands that take a long time to complete (such as heating from amb
 
 The Python API only restricts module placement based on physical limitations. Protocol Designer can only place one of each type of module on the deck, except the Temperature Module. [`ProtocolContext.load_module()`](https://docs.opentrons.com/v2/new_protocol_api.html#opentrons.protocol_api.ProtocolContext.load_module) allows placing any powered module in any column 1 or 3 slot (except the Thermocycler Module, which only fits in slots A1 and B1). And it allows placing Magnetic Blocks in any working area slot.
 
+#### Liquid level detection
+
+Sensors in Flex pipettes can detect the level of liquid in a well. You can use this feature to target a [liquid meniscus](https://docs.opentrons.com/v2/robot_position.html?highlight=liquid+level#meniscus) during a pipetting action.
+
 #### Python packages
 
 Not only does the Python API support some features not included in Protocol Designer, but every Python protocol *is a Python script*, which means that it can perform any computation that relies on the Python standard libraries or the suite of libraries included in the Flex system software.

docs/flex-manual/docs/system-description.md

@@ -393,7 +393,7 @@ A photointerruptor switch detects the position of the pipette's tip ejector mech
 
 #### Pressure sensors
 
-Flex pipettes use internal pressure sensors to detect liquid in well plates, reservoirs, and tubes. Liquid detection takes place as a pipette approaches the surface of a liquid. Sensors in the pipettes detect pressure changes relative to ambient pressure. A particular change in pressure tells the robot that liquid is present in a well and the pipette tip is in contact with the liquid's surface.
+Flex pipettes use internal pressure sensors to detect liquid in well plates, reservoirs, and tubes. Liquid detection takes place as a pipette approaches the surface of a liquid. Sensors in the pipettes detect pressure changes relative to ambient pressure. Particular changes in pressure tells the robot whether liquid is present in a well, the liquid level, and if the pipette tip is in contact with the liquid's surface.
 
 1-channel pipettes have one pressure sensor. The 8-channel pipette pressure sensors are on channels 1 and 8 (positions A1 and H1). The 96-channel pipette pressure sensors are on channels 1 and 96 (positions A1 and H12). Other channels on multi-channel pipettes do not have sensors and cannot detect liquid.