Clarify the README files for the various separate TAP-based test suites.

Explain the difference between "make check" and "make installcheck".
Mention the need for --enable-tap-tests (only some of these did so
before).  Standardize their wording about how to run the tests.

src/test/authentication/README

@@ -11,10 +11,16 @@ are more complicated, and are not safe to run in a multi-user system.
 Running the tests
 =================
 
-    make check
+NOTE: You must have given the --enable-tap-tests argument to configure.
 
+Run
+    make check
 or
-
     make installcheck
+You can use "make installcheck" if you previously did "make install".
+In that case, the code in the installation tree is tested.  With
+"make check", a temporary installation tree is built from the current
+sources and then tested.
 
-NOTE: This requires the --enable-tap-tests argument to configure.
+Either way, this test initializes, starts, and stops a test Postgres
+cluster.

src/test/kerberos/README

@@ -16,11 +16,19 @@ users.
 Running the tests
 =================
 
-    make check
+NOTE: You must have given the --enable-tap-tests argument to configure.
 
+Run
+    make check
 or
-
     make installcheck
+You can use "make installcheck" if you previously did "make install".
+In that case, the code in the installation tree is tested.  With
+"make check", a temporary installation tree is built from the current
+sources and then tested.
+
+Either way, this test initializes, starts, and stops a test Postgres
+cluster, as well as a test KDC server.
 
 Requirements
 ============
@@ -30,6 +38,6 @@ supported.
 
 Debian/Ubuntu packages: krb5-admin-server krb5-kdc krb5-user
 
-RHEL/CentOS packages: krb5-server krb5-workstation
+RHEL/CentOS/Fedora packages: krb5-server krb5-workstation
 
 FreeBSD port: krb5 (base system has Heimdal)

src/test/ldap/README

@@ -17,11 +17,19 @@ users.
 Running the tests
 =================
 
-    make check
+NOTE: You must have given the --enable-tap-tests argument to configure.
 
+Run
+    make check
 or
-
     make installcheck
+You can use "make installcheck" if you previously did "make install".
+In that case, the code in the installation tree is tested.  With
+"make check", a temporary installation tree is built from the current
+sources and then tested.
+
+Either way, this test initializes, starts, and stops a test Postgres
+cluster, as well as a test LDAP server.
 
 Requirements
 ============

src/test/recovery/README

@@ -8,14 +8,16 @@ This directory contains a test suite for recovery and replication.
 Running the tests
 =================
 
-    make check
+NOTE: You must have given the --enable-tap-tests argument to configure.
 
+Run
+    make check
 or
-
     make installcheck
+You can use "make installcheck" if you previously did "make install".
+In that case, the code in the installation tree is tested.  With
+"make check", a temporary installation tree is built from the current
+sources and then tested.
 
-NOTE: This creates a temporary installation (in the case of "check"),
-and some tests may create one or multiple nodes, be they master or
-standby(s) for the purpose of the tests.
-
-NOTE: This requires the --enable-tap-tests argument to configure.
+Either way, this test initializes, starts, and stops several test Postgres
+clusters.

src/test/ssl/README

@@ -7,20 +7,27 @@ This directory contains a test suite for SSL support. It tests both
 client-side functionality, i.e. verifying server certificates, and
 server-side functionality, i.e. certificate authorization.
 
+CAUTION: The test server run by this test is configured to listen for
+TCP connections on localhost. Any user on the same host is able to
+log in to the test server while the tests are running. Do not run this
+suite on a multi-user system where you don't trust all local users!
+
 Running the tests
 =================
 
-    make check
+NOTE: You must have given the --enable-tap-tests argument to configure.
 
+Run
+    make check
 or
-
     make installcheck
+You can use "make installcheck" if you previously did "make install".
+In that case, the code in the installation tree is tested.  With
+"make check", a temporary installation tree is built from the current
+sources and then tested.
 
-NOTE: This creates a temporary installation (in the case of "check"),
-and sets it up to listen for TCP connections on localhost. Any user on
-the same host is allowed to log in to the test installation while the
-tests are running. Do not run this suite on a multi-user system where
-you don't trust all local users!
+Either way, this test initializes, starts, and stops a test Postgres
+cluster that is accessible to other local users!
 
 Certificates
 ============

src/test/subscription/README

@@ -8,16 +8,16 @@ This directory contains a test suite for subscription/logical replication.
 Running the tests
 =================
 
-    make check
+NOTE: You must have given the --enable-tap-tests argument to configure.
 
+Run
+    make check
 or
-
     make installcheck
+You can use "make installcheck" if you previously did "make install"
+(including installing the hstore extension).  In that case, the code
+in the installation tree is tested.  With "make check", a temporary
+installation tree is built from the current sources and then tested.
 
-This requires the --enable-tap-tests argument to configure.
-
-Running the tests creates a temporary installation (in the case of
-"check"), and some tests may create one or multiple nodes, for the
-purpose of the tests.
-
-Running installcheck requires the hstore extension to be installed.
+Either way, this test initializes, starts, and stops several test Postgres
+clusters.