Adjust caches documentation

 * Fix typos
 * Remove obsolete stuff
 * Add a note on caches potentially shared between session factories
 * Link each cache to its configuration documentation
 * Give ids to all sections
 * Switch Memcache for EnyimMemcached and document it. The former is
   no more maintained since years, and its NuGet package is not updated.
   Moreover it fails some basic tests.
   The later appears to be no more maintained since one year and a half,
   but it does not fail tests and its NuGet package is still updated.

Author: fredericDelaporte

doc/reference/modules/nhibernate_caches.xml

@@ -9,7 +9,7 @@
 			<title>NHibernate.Caches namespace contains several second-level cache providers for NHibernate.</title>
 
 			<para>
-				A cache is place where entities are kept after being loaded from the database; once cached, they can be
+				A cache is a place where entities are kept after being loaded from the database; once cached, they can be
 				retrieved without going to the database. This means that they are faster to (re)load.
 			</para>
 
@@ -35,6 +35,12 @@
 			the same entity without hitting the database each time; hence the performance gain.
 		</para>
 
+		<para>
+			Depending on the chosen cache provider, the second level cache may be actually shared between different session
+			factories. If you need to avoid this for some session factories, configure each of them with a different
+			<literal>cache.region_prefix</literal>. See <xref linkend="configuration-optional" />.
+		</para>
+
 		<para>
 			Several cache providers have been contributed by NHibernate users:
 			<variablelist>
@@ -45,6 +51,7 @@
 							Uses <classname>Bamboo.Prevalence</classname> as the cache provider. Open the
 							file <filename>Bamboo.Prevalence.license.txt</filename> for more information about its license;
 							you can also visit its <ulink url="http://bbooprevalence.sourceforge.net/">website</ulink>.
+							Also see <xref linkend="NHibernate.Caches.Prevalence" />.
 						</para>
 					</listitem>
 				</varlistentry>
@@ -55,6 +62,7 @@
 							Uses <classname>System.Web.Caching.Cache</classname> as the cache provider. This means that you can
 							rely on ASP.NET caching feature to understand how it works. For more information, read (on the MSDN):
 							<ulink url="https://msdn.microsoft.com/en-us/library/6hbbsfk6.aspx">Caching Application Data</ulink>.
+							Also see <xref linkend="NHibernate.Caches.SysCache" />.
 						</para>
 					</listitem>
 				</varlistentry>
@@ -69,14 +77,17 @@
 						<para>
 							SysCache2 requires Microsoft SQL Server 2000 or higher.
 						</para>
+						<para>
+							See <xref linkend="NHibernate.Caches.SysCache2" />.
+						</para>
 					</listitem>
 				</varlistentry>
 				<varlistentry>
-					<term><classname>NHibernate.Caches.MemCache</classname></term>
+					<term><classname>NHibernate.Caches.EnyimMemcached</classname></term>
 					<listitem>
 						<para>
-							Uses <literal>memcached</literal>. See <ulink url="https://memcached.org/">memcached homepage</ulink>
-							for more information.
+							Uses <literal>Memcached</literal>. See <ulink url="https://memcached.org/">memcached homepage</ulink>
+							for more information on Memcached. Also see <xref linkend="NHibernate.Caches.EnyimMemcached" />.
 						</para>
 					</listitem>
 				</varlistentry>
@@ -96,6 +107,7 @@
 					<listitem>
 						<para>
 							Uses <classname>System.Runtime.Caching.MemoryCache.Default</classname> as the cache provider.
+							See <xref linkend="NHibernate.Caches.RtMemoryCache" />.
 						</para>
 					</listitem>
 				</varlistentry>
@@ -111,17 +123,16 @@
 			<itemizedlist>
 				<listitem>
 					<para>
-						Choose the cache provider you want to use and copy its assembly in your assemblies directory
-						(<filename>NHibernate.Caches.Prevalence.dll</filename> or
-						<filename>NHibernate.Caches.SysCache.dll</filename>).
+						Choose the cache provider you want to use and copy its assembly in your assemblies directory.
+						(For example, <filename>NHibernate.Caches.Prevalence.dll</filename> or
+						<filename>NHibernate.Caches.SysCache.dll</filename>.)
 					</para>
 				</listitem>
 				<listitem>
 					<para>
 						To tell NHibernate which cache provider to use, add in your NHibernate configuration file
 						(can be <filename>YourAssembly.exe.config</filename> or <filename>web.config</filename> or a
-						<filename>.cfg.xml</filename> file, in the latter case the syntax will be different from what
-						is shown below):
+						<filename>.cfg.xml</filename> file):
 						<programlisting>
 &lt;property name="cache.provider_class"&gt;<literal>XXX</literal>&lt;/property&gt;<co id="hibernate.cache.provider_class-co" linkends="hibernate.cache.provider_class"/>
 &lt;property name="cache.default_expiration"&gt;<literal>120</literal>&lt;/property&gt;<co id="nhcaches-expiration-co" linkends="nhcaches-expiration"/>
@@ -312,7 +323,7 @@
 </configSections>]]></programlisting>
 		</example>
 
-		<section>
+		<section id="NHibernate.Caches.SysCache2-Table">
 			<title>Table-based Dependency</title>
 
 			<para>
@@ -369,7 +380,7 @@
 			</varlistentry>
 		</variablelist>
 
-		<section>
+		<section id="NHibernate.Caches.SysCache2-Command">
 			<title>Command-Based Dependencies</title>
 
 			<para>
@@ -464,7 +475,7 @@
 			</variablelist>
 		</section>
 
-		<section>
+		<section id="NHibernate.Caches.SysCache2-Aggregate">
 			<title>Aggregate Dependencies</title>
 
 			<para>
@@ -508,7 +519,7 @@
 			</example>
 		</section>
 
-		<section>
+		<section id="NHibernate.Caches.SysCache2-AdditionalSettings">
 			<title>Additional Settings</title>
 			<para>
 				In addition to data dependencies for the cache regions, time based expiration policies can be specified
@@ -571,7 +582,15 @@
 				</varlistentry>
 			</variablelist>
 		</section>
+	</section>
 
+	<section id="NHibernate.Caches.EnyimMemcached">
+		<title>EnyimMemcached Configuration</title>
+		<para>
+			Its configuration relies on the EnyimMemcached library own configuration, through its
+			<literal>enyim.com/memcached</literal> configuration section. See
+			<ulink url="https://github.com/enyim/EnyimMemcached">project site</ulink>.
+		</para>
 	</section>
 
 	<section id="NHibernate.Caches.RtMemoryCache">