MINOR: Fix warnings in streams javadoc

[mimaison]

Fixes the following warnings (./gradlew streams:javadoc):

> Task :streams:javadoc
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/processor/assignment/TaskAssignor.java:74: warning - @param argument "assignment:" is not a parameter name.
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/processor/assignment/TaskAssignor.java:74: warning - @param argument "subscription:" is not a parameter name.
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/processor/assignment/TaskAssignor.java:74: warning - @param argument "error:" is not a parameter name.
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java:663: warning - Missing closing '}' character for inline tag: "{@code auto.include.jmx.reporter"
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java:663: warning - Tag @link: reference not found: JMX_REPORTER "jmx.reporter"
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java:579: warning - Missing closing '}' character for inline tag: "{@code default.windowed.key.serde.inner"
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java:587: warning - Missing closing '}' character for inline tag: "{@code default.windowed.value.serde.inner"
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java:663: warning - Tag @link: reference not found: JMX_REPORTER "jmx.reporter"
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java:663: warning - Tag @link: reference not found: JMX_REPORTER "jmx.reporter"
/Users/mickael/github/kafka/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java:663: warning - Tag @link: reference not found: JMX_REPORTER "jmx.reporter"

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[chia7712]

LGTM

[mjsax]

Thanks for the cleanup! Highly appreciated!