Convert "Foundry notes" in descriptions to using `<secret>` blocks

[arbron]

A number of items have Foundry implementation notes for users in addition to their normal descriptions. These notes should be moved inside <secret> blocks so they only show up for the owner and not in chat messages.

[arbron]

Here are some class ones I found:

• [x] Bardic Inspiration
• [x] Font of Inspiration
• [x] Channel Divinity (Cleric)
• [x] Channel Divinity (Paladin)
• [x] Ki
• [x] Deflect Missiles
• [x] Favored Enemy
• [x] Natural Explorer
• [x] Font of Magic
• [x] Spell Mastery

[arbron]

• [x] Sling Bullet
• [x] Necklace of Prayer Beads
• [x] Ring of Regeneration
• [x] Ring of the Ram
• [x] Robe of Useful Items
• [x] Potion of Poison
• [x] Potion of Heroism
• [x] Restorative Ointment
• [x] Rod of Absorption
• [x] Feather Token Bird
• [x] Necklace of Fireballs
• [x] Sovereign Glue
• [x] Defender Swords
• [x] Dwarven Thrower
• [x] Mace of Smiting
• [x] Nine Lives Stealer Swords
• [x] Staff of Fire
• [x] Staff of Frost
• [x] Staff of Charming
• [x] Staff of Healing
• [x] Staff of Striking
• [x] Staff of Power
• [x] Staff of Swarming Insects
• [x] Staff of the Magi
• [x] Staff of the Woodlands
• [x] Staff of Withering
• [x] Unarmed Strike Monk
• [x] Breath Weapon
• [x] Savage Attacks