* change IndexMerge proposal title * add proposal links in README.md * move links of the three proposals to the completed part * fix endline of proposal "access a table using multiple indexes" * move ddl and table partion to the completed part
* change IndexMerge proposal title * add proposal links in README.md * move links of the three proposals to the completed part * fix endline of proposal "access a table using multiple indexes" * move ddl and table partion to the completed part