Fix a offline search issue that escaped HTML entities is shown

[tekezo]

This PR fixes a offline search issue that escaped HTML entities is shown as follows, and adds two configuration options.

Fix an issue

Before:

After:

Add configuration options

• offlineSearchSummaryLength which changes the summary length.
• offlineSearchMaxResults which changes the maximum result count.

[medyagh]

thank you for adding this feature, does it would it paginate if the results are more than the screen? if not it still a great PR ! thank you

[tekezo]

@medyagh I'm not planned to add pagination because lunr.js always returns entire results.
So, the pagination will reduce only the rendering cost.

[medyagh]

@medyagh I'm not planned to add pagination because lunr.js always returns entire results.
So, the pagination will reduce only the rendering cost.

sounds good, I look forward for this PR to be merged ! I would like to use this feature