note content features: add chapters to notes

[ugcasa]

note.sh content: add/rm chapters to notes

Adds/removes stuff to notes.

usage:     note content [add|rm] <date> <header> <string>
  <date>        syntax: 20190131, yesterday, next monday..
                without date actions points to current date note
  <header>      level 2 markdown chapter
  <string>      chapter content
example:
           a) guru note content add "Cheap opensource LIDAR project" "Nice! https://hackaday.com/2020/lidis.html"
           b) guru note content add 20201012 Hammaslääkäri klo 12:45 kanneltalo
           c) guru note content rm "Cheap opensource LIDAR project"

produces following:

a)

## Cheap opensource LIDAR project

Nice!

-https://hackaday.com/2020/lidis.html


## Change log

 date              | author | change
:----------------- |:------:|:------
 20200325-01:41:41 | casa   | created
 20200325-01:41:41 | casa   | tags added
 20200325-01:41:52 | casa   | chapter 'Cheap opensource LIDAR project' added

b)

## Hammaslääkäri klo 12:45 kanneltalo


## Change log
 date              | author | change
:----------------- |:------:|:------
 20200325-01:41:41 | casa   | created
 20200325-01:41:41 | casa   | tags added
 20200325-01:41:52 | casa   | chapter 'Cheap opensource LIDAR project' added
 20200325-02:32:55 | casa   | chapter 'Hammaslääkäri klo 12:45 kanneltalo' added

c)

 date              | author | change
:----------------- |:------:|:------
 20200325-01:41:41 | casa   | created
 20200325-01:41:41 | casa   | tags added
 20200325-01:41:52 | casa   | chapter 'Cheap opensource LIDAR project' added
 20200325-02:32:55 | casa   | chapter 'Hammaslääkäri klo 12:45 kanneltalo' added
 20200325-03:45:12 | casa   | chapter 'Cheap opensource LIDAR project' removed

needed actions:

headers:    "## $header\n\n"
links:      "\n-$link"
content     "$content\n\n"