Add documentation of get_approximate_size for Python, Ruby, and Go

This was missed from original PR #1756, where only C API was documented.

bindings/go/src/fdb/transaction.go

@@ -383,6 +383,9 @@ func (t *transaction) getApproximateSize() FutureInt64 {
 	}
 }
 
+// Returns a future that is the approximate transaction size so far in this
+// transaction, which is the summation of the estimated size of mutations,
+// read conflict ranges, and write conflict ranges.
 func (t Transaction) GetApproximateSize() FutureInt64 {
 	return t.getApproximateSize()
 }

documentation/sphinx/source/api-common.rst.inc

@@ -176,6 +176,9 @@
 .. |transaction-get-committed-version-blurb| replace::
     Gets the version number at which a successful commit modified the database. This must be called only after the successful (non-error) completion of a call to |commit-func| on this Transaction, or the behavior is undefined. Read-only transactions do not modify the database when committed and will have a committed version of -1. Keep in mind that a transaction which reads keys and then sets them to their current values may be optimized to a read-only transaction.
 
+.. |transaction-get-approximate-size-blurb| replace::
+    Gets the the approximate transaction size so far, which is the summation of the estimated size of mutations, read conflict ranges, and write conflict ranges.
+
 .. |transaction-get-versionstamp-blurb| replace::
     Returns a future which will contain the versionstamp which was used by any versionstamp operations in this transaction. This function must be called before a call to |commit-func| on this Transaction. The future will be ready only after the successful completion of a call to |commit-func| on this Transaction. Read-only transactions do not modify the database when committed and will result in the future completing with an error. Keep in mind that a transaction which reads keys and then sets them to their current values may be optimized to a read-only transaction.
 

documentation/sphinx/source/api-python.rst

@@ -796,6 +796,13 @@ Most applications should use the read version that FoundationDB determines autom
 
 .. _api-python-transaction-options:
 
+Transaction misc functions
+--------------------------
+
+.. method:: Transaction.get_approximate_size()
+
+    |transaction-get-approximate-size-blurb|. Returns a :class:`FutureInt64`.
+
 Transaction options
 -------------------
 

documentation/sphinx/source/api-ruby.rst

@@ -738,10 +738,17 @@ Most applications should use the read version that FoundationDB determines autom
 
     |infrequent| |transaction-get-committed-version-blurb|
 
-.. method:: Transaction.get_verionstamp() -> String
+.. method:: Transaction.get_versionstamp() -> String
 
     |infrequent| |transaction-get-versionstamp-blurb|
 
+Transaction misc functions
+--------------------------
+
+.. method:: Transaction.get_approximate_size() -> Int64Future
+
+    |transaction-get-approximate-size-blurb|. Returns a :class:`Int64Future`.
+
 Transaction options
 -------------------