docs: Fix reference on page 2

docs/proposal/intro.Rmd

@@ -4,7 +4,7 @@ Motor neurons are the junction between the central nervous system and the muscul
 knitr::include_graphics(path="images/emg_hardware.png")
 ```
 
-Electromyography (EMG) is used to quantify the net electrical charge of a muscle as it contracts. Invasive electromyography involves the insertion of a needle electrode into the muscle, as pictured in **figure \@ref(fig:emg-hardware)a**. Invasive electromyography is the more commonly used technique, as it allows for deeper muscle groups to be accessed, and the manipulation of the electrode to sample different parts of the muscle and to optimize the signal (@emg_decomposition_tutorial). In non-invasive electromyography, surface electrodes are placed on the skin, as pictured in **figure \@ref(fig:emg-hardware)b**, and voltage is measured as participants flex and relax a muscle (@emg_decomposition_tutorial). This technique is the one that the capstone partner is interested in, and has advantages that include ease-of-use and more flexible applications. In addition, recent advances in technology and data science have increased the utility of non-invasive EMG, as raw EMG signals can now be decomposed into their constituent individual motor unit action potentials, whereas this was previously only feasible with invasive EMG [negro_muceli_castronovo_holobar_farina_2016].
+Electromyography (EMG) is used to quantify the net electrical charge of a muscle as it contracts. Invasive electromyography involves the insertion of a needle electrode into the muscle, as pictured in **figure \@ref(fig:emg-hardware)a**. Invasive electromyography is the more commonly used technique, as it allows for deeper muscle groups to be accessed, and the manipulation of the electrode to sample different parts of the muscle and to optimize the signal (@emg_decomposition_tutorial). In non-invasive electromyography, surface electrodes are placed on the skin, as pictured in **figure \@ref(fig:emg-hardware)b**, and voltage is measured as participants flex and relax a muscle (@emg_decomposition_tutorial). This technique is the one that the capstone partner is interested in, and has advantages that include ease-of-use and more flexible applications. In addition, recent advances in technology and data science have increased the utility of non-invasive EMG, as raw EMG signals can now be decomposed into their constituent individual motor unit action potentials, whereas this was previously only feasible with invasive EMG [@negro_muceli_castronovo_holobar_farina_2016].
 
 ```{r emg-decomposition, echo=FALSE, fig.cap = "Decomposition of surface EMG signal into individual motor unit action potential spike trains (De Luca et al. (2006).", fig.align="center", out.width="70%"}
 knitr::include_graphics(path="images/emg_decomposition.png")