Merge pull request rails#50635 from ghiculescu/connection-pool-docs

Minor improvements to Connection Pool docs

Author: p8

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -68,12 +68,10 @@ def db_config
     # Connections can be obtained and used from a connection pool in several
     # ways:
     #
-    # 1. Simply use {ActiveRecord::Base.connection}[rdoc-ref:ConnectionHandling.connection]
-    #    as with Active Record 2.1 and
-    #    earlier (pre-connection-pooling). Eventually, when you're done with
-    #    the connection(s) and wish it to be returned to the pool, you call
+    # 1. Simply use {ActiveRecord::Base.connection}[rdoc-ref:ConnectionHandling.connection].
+    #    When you're done with the connection(s) and wish it to be returned to the pool, you call
     #    {ActiveRecord::Base.connection_handler.clear_active_connections!}[rdoc-ref:ConnectionAdapters::ConnectionHandler#clear_active_connections!].
-    #    This will be the default behavior for Active Record when used in conjunction with
+    #    This is the default behavior for Active Record when used in conjunction with
     #    Action Pack's request handling cycle.
     # 2. Manually check out a connection from the pool with
     #    {ActiveRecord::Base.connection_pool.checkout}[rdoc-ref:#checkout]. You are responsible for

guides/source/configuring.md

@@ -3614,7 +3614,7 @@ Below is a comprehensive list of all the initializers found in Rails in the orde
 Database Pooling
 ----------------
 
-Active Record database connections are managed by `ActiveRecord::ConnectionAdapters::ConnectionPool` which ensures that a connection pool synchronizes the amount of thread access to a limited number of database connections. This limit defaults to 5 and can be configured in `database.yml`.
+Active Record database connections are managed by [`ActiveRecord::ConnectionAdapters::ConnectionPool`][] which ensures that a connection pool synchronizes the amount of thread access to a limited number of database connections. This limit defaults to 5 and can be configured in `database.yml`.
 
 ```yaml
 development:
@@ -3641,6 +3641,7 @@ connection pool by incrementing the `pool` option in `database.yml`
 
 NOTE. If you are running in a multi-threaded environment, there could be a chance that several threads may be accessing multiple connections simultaneously. So depending on your current request load, you could very well have multiple threads contending for a limited number of connections.
 
+[`ActiveRecord::ConnectionAdapters::ConnectionPool`]: https://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/ConnectionPool.html
 
 Custom Configuration
 --------------------