Complete Milestone 7 crafting and portal guide (#79)

README.md

@@ -105,6 +105,20 @@ JEI is optional; vanilla crafting
 recipes and all writing interactions work without it. For a development client
 with JEI, run `./gradlew runClient -PwithJei=true`.
 
+Four Crystal Shards craft one Crystal Block; eight Crystal Blocks around an
+empty crafting-grid center make one Book Receptacle. Picking up a shard unlocks
+the block recipe, and picking up a block unlocks the Receptacle recipe. The
+existing Ink Vial recipe uses two black dyes, a glass bottle, and a water
+bucket; the empty bucket stays in the crafting grid. These JSON recipes appear
+in JEI when it is installed and can be replaced by a data pack at
+`data/rivencraft/recipe/<recipe_name>.json`. To test a replacement, use a fresh
+world or `/reload`, then check the result in a crafting table and vanilla
+Crafter. A vanilla Lectern converts to a Rivencraft Book Stand when a Rivencraft
+book or page is placed on it; this in-world interaction has no JEI guide.
+With Create installed, Crystal Blocks and Book Receptacles have an optional Ponder scene
+showing crystal-frame construction, book activation, and a parrot crossing the portal. Use the Ponder shortcut
+while hovering either item; Rivencraft does not require Create to run.
+
 Craft a Book Binder from three iron ingots and five planks. Put leather or an
 empty Notebook in the left cover slot. Enter a title, then place a Link Panel
 Page first in the horizontal page strip. Click a page in the strip with a