Improve English labels for buglink RegExes

The purpose of those regular expressions was really unclear and lacked
documentation. The German translation was actually better than the
original English one, including a better description with explanation
and example.

Signed-off-by: Damien Regad <[email protected]>

Original commit message reworded.

Author: okainov

Source/lang/strings_english.txt

@@ -85,10 +85,10 @@ $s_plugin_Source_view_threshold = 'View Threshold';
 $s_plugin_Source_update_threshold = 'Update Threshold';
 $s_plugin_Source_manage_threshold = 'Manage Threshold';
 $s_plugin_Source_username_threshold = 'Set Username Threshold';
-$s_plugin_Source_buglink_regex_1 = 'Bug Link Regex Pass 1';
-$s_plugin_Source_buglink_regex_2 = 'Bug Link Regex Pass 2';
-$s_plugin_Source_bugfix_regex_1 = 'Bug Fixed Regex Pass 1';
-$s_plugin_Source_bugfix_regex_2 = 'Bug Fixed Regex Pass 2';
+$s_plugin_Source_buglink_regex_1 = '<abbr title="Regular Expression">RegExp</abbr> for parsing links to issues (1)<br/><span class="small">It will be used for parsing string containing some issues i.e. "Issues #3, #87"</span>';
+$s_plugin_Source_buglink_regex_2 = '<abbr title="Regular Expression">RegExp</abbr> for parsing links to issues (2)<br/><span class="small">It will be applied to the result of expression 1 to extract exact issues ID (i.e. "3", "87")</span>';
+$s_plugin_Source_bugfix_regex_1 = '<abbr title="Regular Expression">RegExp</abbr> for parsing resolved issues (1)<br/><span class="small">It will be used for parsing string containing some resolved issues i.e. "Fixes #21 #35"</span>';
+$s_plugin_Source_bugfix_regex_2 = '<abbr title="Regular Expression">RegExp</abbr> for parsing resolved issues (2)<br/><span class="small">It will be applied to the result of expression 1 to extract exact issues ID (i.e. "21", "35")</span>';
 $s_plugin_Source_bugfix_status = 'Bug Fixed Status';
 $s_plugin_Source_bugfix_status_pvm = 'Bug Fixed Product Status';
 $s_plugin_Source_bugfix_status_off = '[Disabled]';