Add recipe for kvass (#374)

* Create kvass.md

* Update src/kvass.md

Co-authored-by: Zyansheep <zyansheep@gmail.com>

Co-authored-by: Zyansheep <zyansheep@gmail.com>

src/kvass.md

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+# Kvass
+
+[Kvass](https://en.wikipedia.org/wiki/Kvass) is a Slavic fermented beverage which is both simple to make and rich in flavour.
+
+- ⏲️ Prep time: ~30 min
+- ⌛ Fermentation time: ~1 week
+
+## Ingredients
+
+- 100 g of raisins
+- 100 g of sugar
+- 3 slices of black bread (e.g. pumpernickel bread, rye bread)
+- 1-2 lemons
+- 1 pkg (7 g) of active dry yeast
+- *Optional:*
+  - *A handful of coffee beans*
+  - *Non-citrus fruits (e.g. plums, apples, kiwi)*
+
+## Directions
+
+1. Bring 1 L of water in a pot to a boil.
+2. Burn black bread in a toaster or in an oven until it is thoroughly scorched to blackness on the outside.
+3. Once the water has come to boil, remove off heat. Add burned black bread, a handful of raisins, a few slices of lemon, and coffee beans to the pot.
+4. Leave contents of the pot to cool down to room temperature.
+5. Filter out everything from the pot through a strainer, and pour contents into a separate, sterilized container. Add sugar and yeast into
+the container, and stir until sugar is dissolved. This starts the fermentation process. The amount of sugar in this recipe should yield 1.0%-2.5% alcohol
+by total volume at the end of the fermentation process.
+6. Add rest of raisins, and non-citrus fruits of your choice. The fruits will positively impact flavour of the final product.
+7. If mixture is not already in a mason jar, pour the mixture into a sterile mason jar, and seal the lid. Place the jar in a warm place (26-30°C; 79-86°F),
+and let it ferment for a week, or until it stops bubbling.
+8. Remove all raisins and fruits from the jar.
+9. Squeeze lemon juice from lemons into the mixture. You may drink the now-complete kvass right away, or refrigerate it before drinking.
+
+## Contribution
+
+- Holsterbau - [website](https://github.com/Holsterbau)
+
+;tags: drink