spanner: Remove read-only client ref
As discussed in
we should remove the reference to creating a read-only client from
CHANGES.md.
not affected by this change.
- Spanner clients that are created with the NewClient method will now default
to a write sessions fraction of 0.2 in the pool
- (i.e. SessionPoolConfig.WriteSessions=0.2). Creating Spanner clients for
- read-only purposes should be done using NewClientWithConfig with
- SessionPoolConfig.WriteSessions=0.0.
+ (i.e. SessionPoolConfig.WriteSessions=0.2).
Spanner clients that are created with the NewClientWithConfig method are
not affected by this change.
- The session pool maintenance worker has been improved so it keeps better
