Fix 2 typos in lang/c++/api/ValidSchema.hh:

[areese]

1. minumum -> minimum
2. valididated -> validated

Fix 1 typo in lang/c++/api/GenericDatum.hh:

1. appropraite -> appropriate

Fix 3 typos in lang/c++/api/Decoder.hh:

1. fiedls -> fields
2. arbitray -> arbitrary
3. funtions -> functions

Fix 3 typos in lang/c++/api/DataFile.hh:

1. opportinity -> opportunity
2. entires -> entries
3. desrialize -> deserialize

Make sure you have checked all steps below.

Jira

• My PR addresses the following Avro Jira issues and references them in the PR title. For example, "AVRO-1234: My Avro PR"
  • https://issues.apache.org/jira/browse/AVRO-XXX
  • In case you are adding a dependency, check if the license complies with the ASF 3rd Party License Policy.

Tests

• My PR adds the following unit tests OR does not need testing for this extremely good reason:
  This PR only fixes typo's in the c++ documentation built from the comments.

Commits

• My commits all reference Jira issues in their subject lines. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain Javadoc that explain what it does

[areese]

Travis build failed to download artifacts from maven under java 8:

[ERROR] Failed to execute goal on project avro-grpc: Could not resolve dependencies for project org.apache.avro:avro-grpc:bundle:1.11.0-SNAPSHOT: Failed to collect dependencies at io.grpc:grpc-core:jar:1.33.1: Failed to read artifact descriptor for io.grpc:grpc-core:jar:1.33.1: Could not transfer artifact io.grpc:grpc-core:pom:1.33.1 from/to central (https://repo.maven.apache.org/maven2): Transfer failed for https://repo.maven.apache.org/maven2/io/grpc/grpc-core/1.33.1/grpc-core-1.33.1.pom: Connection reset -> [Help 1]

[RyanSkraba]

Thanks for this improvement!