Fix typos in multiple files

[Marcofann]

This pull request addresses various typos found across multiple files in the repository. The following changes have been made:

• In "genesis.go": Corrected the usage of "a identifier" to "an identifier" to follow grammatical rules.
• In "README.md" (multiple instances): Fixed the incorrect usage of "a initialized" to "an initialized" and "an up-to-date" to "a up-to-date".
• In "Developing.md" (multiple instances): Corrected the usage of "a absolute path" to "an absolute path".
• In other files: Similar typos have been fixed across various other documentation files in the cosmwasm/contracts/v010/ directory.