[DMG] General fixes and typos

[NickVendel]

• - Standard firearms' Reload weapon property doesn't specify number of shots that can be taken before a reload. [MISC] Errata - Sage Advice Compendium v2.7 + General Fixes #120
• - Gunpowder description is full of typos, on both keg and powder horn variants. [DMG] Fixes to Gunpowder, Sword of Sharpness, and Pearl of Power #308
• - Sentinel Shield is missing rules for bonus to Passive Perception. [DMG] Fixes to Gunpowder, Sword of Sharpness, and Pearl of Power #308
• - Sword of Sharpness uses SRD's "extra 4d6 damage" instead of DMG's "extra 14 damage". [DMG] Fixes to Gunpowder, Sword of Sharpness, and Pearl of Power #308
• - Drow Poison has a "draw" typo in the description. Reported by fayegrimreaper on Discord [DMG] Fixed typos in description for Truth Serum  #279
• - Truth Serum's description has some missing parts. [DMG] Fixed typos in description for Truth Serum  #279
• - Berserker Axe is missing both enhancement setter and stat for HP bonus. Reported by jarod8787 on Discord [DMG] Fixed Berserker Axe #307
• - Pearl of Power has a duplicated sentence "If the expended slot was of 4th level or higher, the new slot is 3rd level" in its description [DMG] Typos and Fixes #295 [DMG] Fixes to Gunpowder, Sword of Sharpness, and Pearl of Power #308