Added example to README. Added text search configuratio test

Author: Artur Zakirov

README.md

@@ -22,22 +22,40 @@ Typical installation procedure may look like this:
 After this you can create your own text search configuration:
 
 ```sql
-CREATE TEXT SEARCH CONFIGURATION russian_ts (
+CREATE TEXT SEARCH CONFIGURATION english_ts (
     PARSER = tsparser
 );
 
-COMMENT ON TEXT SEARCH CONFIGURATION russian_ts IS 'text search configuration for russian language';
+COMMENT ON TEXT SEARCH CONFIGURATION english_ts IS 'text search configuration for english language';
 
-ALTER TEXT SEARCH CONFIGURATION russian_ts
+ALTER TEXT SEARCH CONFIGURATION english_ts
     ADD MAPPING FOR email, file, float, host, hword_numpart, int,
     numhword, numword, sfloat, uint, url, url_path, version
     WITH simple;
 
-ALTER TEXT SEARCH CONFIGURATION russian_ts
-    ADD MAPPING FOR asciiword, asciihword, hword_asciipart
-    WITH russian_stem, english_stem;
+ALTER TEXT SEARCH CONFIGURATION english_ts
+    ADD MAPPING FOR asciiword, asciihword, hword_asciipart,
+    word, hword, hword_part
+    WITH english_stem;
+```
+
+## Examples
+
+The difference between **tsparser** and **default** parsers is that **tsparser**
+gives also unbroken words by underscore character.
 
-ALTER TEXT SEARCH CONFIGURATION russian_ts
-    ADD MAPPING FOR word, hword, hword_part
-    WITH russian_stem, russian_stem;
+For example:
+
+```sql
+SELECT to_tsvector('english_ts', 'pg_trgm');
+         to_tsvector
+-----------------------------
+ 'pg':2 'pg_trgm':1 'trgm':3
+(1 row)
+
+SELECT to_tsvector('english', 'pg_trgm');
+   to_tsvector
+-----------------
+ 'pg':1 'trgm':2
+(1 row)
 ```

expected/pg_tsparser.out

@@ -175,3 +175,21 @@ SELECT * FROM ts_parse('tsparser', '345 qwe@efd.r '' http://www.com/ http://aew.
      1 | qwerty
 (139 rows)
 
+-- Test text search configuration with parser
+CREATE TEXT SEARCH CONFIGURATION english_ts (
+    PARSER = tsparser
+);
+ALTER TEXT SEARCH CONFIGURATION english_ts
+    ADD MAPPING FOR email, file, float, host, hword_numpart, int,
+    numhword, numword, sfloat, uint, url, url_path, version
+    WITH simple;
+ALTER TEXT SEARCH CONFIGURATION english_ts
+    ADD MAPPING FOR asciiword, asciihword, hword_asciipart,
+    word, hword, hword_part
+    WITH english_stem;
+SELECT to_tsvector('english_ts', 'pg_trgm');
+         to_tsvector         
+-----------------------------
+ 'pg':2 'pg_trgm':1 'trgm':3
+(1 row)
+

sql/pg_tsparser.sql

@@ -5,3 +5,20 @@ SELECT * FROM ts_token_type('tsparser');
 SELECT * FROM ts_parse('tsparser', '345 qwe@efd.r '' http://www.com/ http://aew.werc.ewr/?ad=qwe&dw 1aew.werc.ewr/?ad=qwe&dw 2aew.werc.ewr http://3aew.werc.ewr/?ad=qwe&dw http://4aew.werc.ewr http://5aew.werc.ewr:8100/?  ad=qwe&dw 6aew.werc.ewr:8100/?ad=qwe&dw 7aew.werc.ewr:8100/?ad=qwe&dw=%20%32 +4.0e-10 qwe qwe qwqwe 234.435 455 5.005 teodor@stack.net teodor@123-stack.net 123_teodor@stack.net 123-teodor@stack.net qwe-wer asdf <fr>qwer jf sdjk<we hjwer <werrwe> ewr1> ewri2 <a href="qwe<qwe>">
 /usr/local/fff /awdf/dwqe/4325 rewt/ewr wefjn /wqe-324/ewr gist.h gist.h.c gist.c. readline 4.2 4.2. 4.2, readline-4.2 readline-4.2. 234
 <i <b> wow  < jqw <> qwerty');
+
+-- Test text search configuration with parser
+CREATE TEXT SEARCH CONFIGURATION english_ts (
+    PARSER = tsparser
+);
+
+ALTER TEXT SEARCH CONFIGURATION english_ts
+    ADD MAPPING FOR email, file, float, host, hword_numpart, int,
+    numhword, numword, sfloat, uint, url, url_path, version
+    WITH simple;
+
+ALTER TEXT SEARCH CONFIGURATION english_ts
+    ADD MAPPING FOR asciiword, asciihword, hword_asciipart,
+    word, hword, hword_part
+    WITH english_stem;
+
+SELECT to_tsvector('english_ts', 'pg_trgm');