Minor fixes (missing alt-text, uninformative link text, missing anchor)

episodes/02-project-intro.Rmd

@@ -156,7 +156,7 @@ Now we have a good directory structure we will now place/save the data file in t
 
 ## Challenge 3
 
-Download the gapminder data from [here](data/gapminder_data.csv).
+Download the gapminder data from [this link to a csv file](data/gapminder_data.csv).
 
 1. Download the file (right mouse click on the link above -> "Save link as" / "Save file as", or click on the link and after the page loads, press <kbd>Ctrl</kbd>\+<kbd>S</kbd> or choose File -> "Save page as")
 2. Make sure it's saved under the name `gapminder_data.csv`

episodes/08-plot-ggplot2.Rmd

@@ -423,7 +423,7 @@ There are two nice things about `ggsave`. First, it defaults to the last plot, s
 
 This is a taste of what you can do with ggplot2. RStudio provides a
 really useful [cheat sheet][cheat] of the different layers available, and more
-extensive documentation is available on the [ggplot2 website][ggplot-doc]. All RStudio cheat sheets can be found [here][cheat_all].
+extensive documentation is available on the [ggplot2 website][ggplot-doc]. All RStudio cheat sheets are available from the [RStudio website][cheat_all].
 Finally, if you have no idea how to change something, a quick Google search will
 usually send you to a relevant question and answer on Stack Overflow with reusable
 code to modify!

episodes/14-tidyr.Rmd

@@ -110,7 +110,7 @@ Until now, we've been using the nicely formatted original gapminder dataset, but
 'real' data (i.e. our own research data) will never be so well organized. Here
 let's start with the wide formatted version of the gapminder dataset.
 
-> Download the wide version of the gapminder data from [here](data/gapminder_wide.csv)
+> Download the wide version of the gapminder data from [this link to a csv file](data/gapminder_wide.csv)
 > and save it in your data folder.
 
 We'll load the data file and look at it. Note: we don't want our continent and

episodes/15-knitr-markdown.Rmd

@@ -479,7 +479,7 @@ transformed to the formatted appearance (**bold words**) as you type.
 This mode also includes a toolbar at the top with basic formatting buttons,
 similar to what you might see in common word processing software programs.
 You can turn visual editing on and off by pressing
-the ![](fig/visual_mode_icon.png)
+the ![](fig/visual_mode_icon.png){alt='Icon for turning on and off the visual editing mode in RStudio, which looks like a pair of compasses'}
 button in the top right corner of your R Markdown document.
 
 ::::::::::::::::::::::::::::::::::::::::::::::::::

learners/reference.md

@@ -343,7 +343,7 @@ not expected by the programming language.
 
 [type]{#type}
 :   The classification of something in a program (for example, the contents of a variable)
-as a kind of number (e.g. [floating-point](#float), [integer](#integer)), [string](#string),
+as a kind of number (e.g. [floating-point number](#floating-point-number), [integer](#integer)), [string](#string),
 or something else. In R the command typeof() is used to query a variables type.
 
 [while loop]{#while-loop}