Update bom.csv

Makes `x-cable-chain-bracket-alt` properly listed as `optional`

bom.csv

@@ -9,7 +9,7 @@ x-motor-mount,,1,FDM,Download all 3D printed parts at the link at the top of the
 front-drag-chain-mount,,1,FDM,Download all 3D printed parts at the link at the top of the page.,,,
 x-motor-cable-guide,,1,FDM,Download all 3D printed parts at the link at the top of the page.,,,
 x-cable-chain-bracket,,1,FDM,Download all 3D printed parts at the link at the top of the page.,,,
-X-cable-chain-bracket-alt,,-,FDM,Download all 3D printed parts at the link at the top of the page.,,,
+x-cable-chain-bracket-alt,,-,FDM,Download all 3D printed parts at the link at the top of the page.,,Optional, Try this version if x-cable-chain-bracket does not fit your drag-chain well.
 x-gantry-front,,1,FDM,Download all 3D printed parts at the link at the top of the page.,,,
 x-gantry-back,,1,FDM,Download all 3D printed parts at the link at the top of the page.,,,
 x-idler-mount,,1,FDM,Download all 3D printed parts at the link at the top of the page.,,,
@@ -133,4 +133,4 @@ N75-CP40-nozzle-tip,https://www.robotdigg.com/crab/image/2016/09/24/ccdb354070f2
 lubricant-packet,https://www.super-lube.com/content/images/thumbs/0000300_multi-purpose-synthetic-grease-nlgi-00-with-syncolon-8234000_359.jpeg,1,MISC,https://www.super-lube.com/multi-purpose-synthetic-grease-with-syncolon-ptfe-82340,,,"Lubricant is required for the O-rings on the CP40 nozzle holder. Before use, apply lubricant to the end of the nozzle holder and insert into every nozzle tip until the lubricant has coated the inside of the tip and the resistance decreases. Do NOT use white lithium grease for this; it can damage the O-rings."
 rubber-band,https://img.uline.com/is/image/uline/S-15809?$Small$,4,MISC,https://www.uline.com/Product/Detail/S-15809/Desk-Supplies/33-Latex-Free-Rubber-Bands-3-1-2-x-1-8,,,
 zip-tie,https://www.divers-supply.com/media/catalog/product/cache/04f855d5dde875e44e832ab401f00a9d/image/70002c3c4/zip-tie-each.jpeg,15,MISC,https://www.amazon.com/Hmrope-Premium-Plastic-Strength-Self-Locking/dp/B07TG9VMWY/,,,Zip ties that are approx 200mm in length are recommended.
-rubber-feet,https://m.media-amazon.com/images/I/51W3zGnrQzL._AC_SL1000_.jpg,8,MISC,https://www.amazon.com/gp/product/B088HGQSZT/,,,"10mm dia adhesive-backed rubber feet for use on the front-left-leg, front-right-leg, and 2x back-leg"
+rubber-feet,https://m.media-amazon.com/images/I/51W3zGnrQzL._AC_SL1000_.jpg,8,MISC,https://www.amazon.com/gp/product/B088HGQSZT/,,,"10mm dia adhesive-backed rubber feet for use on the front-left-leg, front-right-leg, and 2x back-leg"