Add extrusion thermistor mount (#603)

* Add extrusion thermistor mount

* Update main README

printer_mods/README.md

@@ -282,6 +282,7 @@ like so:
 | rsheng118 | [BTT octopus DIN vertical mount](./rsheng118/BTT_octopus_DIN_vertical_mount) | DIN vertical mount for Big Tech Tree Octopus board | :x: | :x: | :heavy_check_mark: | :x: |
 | ryandam | [Cable Management Duct](./ryandam/Cable_management_duct) | Zip tie mount intergrated cable duct to hide your cable | :heavy_check_mark: | :grey_question: | :grey_question: | :grey_question: | :grey_question: |
 | samwiseg0 | [Microfit 2x3 Skirt Connector (ADXL)](./samwiseg0/microfit_2x3_skirt_connector_adxl) | Mod for a Microfit 2x3 connector to be mounted in a skirt | :x: | :x: | :heavy_check_mark: | :grey_question: | :grey_question: |
+|  | [Extrusion/Chamber Thermistor Mount](./samwiseg0/extrusion_thermistor_mount) | Extrusion mount for a NTC100K Thermistor extrusion | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 |  | [Corsair Flash Voyager GTX Din Mount](./samwiseg0/voyager_gtx_din_mount) | Din carrier for a Corsair Flash Voyager GTX | :x: | :grey_question: | :heavy_check_mark: | :x: | :heavy_check_mark: |
 | See1807 | [TopHat Exhaust and LED Light](./See1807/Voron_V0_Exhaust_and_LED_Mod) | A mount for 10mm LED strips and Exhaust for Voron V0 | :heavy_check_mark: | :x: | :x: | :x: |
 | sse018 | [Octopus DIN Rail bracket](./sse018/Octopus_DIN_Rail_bracket) | A Din rail mount for BTT Octopus board | :x: | :x: |:heavy_check_mark: | :x: |

printer_mods/samwiseg0/extrusion_thermistor_mount/README.md

@@ -0,0 +1,17 @@
+# Extrusion/Chamber Thermistor Mount
+Designed to mount a NTC100K Thermistor Sensor to 2020 extrusions.
+
+
+### Printing
+  * Default voron settings
+  * No supports needed
+
+### BOM
+
+Size | Qty
+--- | ---
+[NTC100K Thermistor](https://www.amazon.com/gp/product/B07QDQXDQ5) | 1
+M3x8 | 1
+M3 T-Nut | 1
+
+![Extrusion/Chamber Thermistor Mount](Images/extrusion_thermistor_holder.png)